# class PG::Connection

The PostgreSQL connection class. The interface for this class is based on libpq, the C application programmer's interface to PostgreSQL. Some familiarity with libpq is recommended, but not necessary.

For example, to send query to the database on the localhost:

    require 'pg'
    conn = PG::Connection.open(:dbname => 'test')
    res = conn.exec_params('SELECT $1 AS a, $2 AS b, $3 AS c', [1, 2, nil])
    # Equivalent to:
    #  res  = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')

See the PG::Result class for information on working with the results of a query.

### Constants

CONNECT_ARGUMENT_ORDER

  The order the options are passed to the ::connect method.

REDIRECT_METHODS

### Public Class Methods

async_api=(enable) click to toggle source

    # File lib/pg/connection.rb, line 280
    def self.async_api=(enable)
            REDIRECT_METHODS.each do |ali, (async, sync)|
                    remove_method(ali) if method_defined?(ali)
                    alias_method( ali, enable ? async : sync )
            end
    end

PG::Connection.conndefaults() → Array click to toggle source

Returns an array of hashes. Each hash has the keys:

`:keyword`

  the name of the option

`:envvar`

  the environment variable to fall back to

`:compiled`

  the compiled in option as a secondary fallback

`:val`

  the option's current value, or `nil` if not known

`:label`

  the label for the field

`:dispchar`

  “” for normal, “D” for debug, and “*” for password

`:dispsize`

  field size

    static VALUE
    pgconn_s_conndefaults(VALUE self)
    {
            PQconninfoOption *options = PQconndefaults();
            VALUE array = pgconn_make_conninfo_array( options );

            PQconninfoFree(options);

            UNUSED( self );

            return array;
    }

conndefaults_hash() click to toggle source

Return the Postgres connection defaults structure as a Hash keyed by option keyword (as a Symbol).

See also conndefaults

    # File lib/pg/connection.rb, line 226
    def self.conndefaults_hash
            return self.conndefaults.each_with_object({}) do |info, hash|
                    hash[ info[:keyword].to_sym ] = info[:val]
            end
    end

PG::Connection.connect_start(connection_hash) → conn click to toggle source
PG::Connection.connect_start(connection_string) → conn
PG::Connection.connect_start(host, port, options, tty, dbname, login, password) → conn

This is an asynchronous version of PG::Connection.connect().

Use connect_poll to poll the status of the connection.

NOTE: this does not set the connection's `client_encoding` for you if Encoding.default_internal is set. To set it after the connection is established, call internal_encoding=. You can also set it automatically by setting ENV, or include the 'options' connection parameter.

    static VALUE
    pgconn_s_connect_start( int argc, VALUE *argv, VALUE klass )
    {
            VALUE rb_conn;
            VALUE conninfo;
            VALUE error;
            t_pg_connection *this;

            /*
             * PG::Connection.connect_start must act as both alloc() and initialize()
             * because it is not invoked by calling new().
             */
            rb_conn  = pgconn_s_allocate( klass );
            this = pg_get_connection( rb_conn );
            conninfo = rb_funcall2( klass, rb_intern("parse_connect_args"), argc, argv );
            this->pgconn = gvl_PQconnectStart( StringValueCStr(conninfo) );

            if( this->pgconn == NULL )
                    rb_raise(rb_ePGerror, "PQconnectStart() unable to allocate structure");

            if ( PQstatus(this->pgconn) == CONNECTION_BAD ) {
                    error = rb_exc_new2(rb_eConnectionBad, PQerrorMessage(this->pgconn));
                    rb_iv_set(error, "@connection", rb_conn);
                    rb_exc_raise(error);
            }

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_conn, pgconn_finish, rb_conn );
            }
            return rb_conn;
    }

PG::Connection.encrypt_password( password, username ) → String click to toggle source

This is an older, deprecated version of encrypt_password. The difference is that this function always uses `md5` as the encryption algorithm.

    static VALUE
    pgconn_s_encrypt_password(VALUE self, VALUE password, VALUE username)
    {
            char *encrypted = NULL;
            VALUE rval = Qnil;

            UNUSED( self );

            Check_Type(password, T_STRING);
            Check_Type(username, T_STRING);

            encrypted = PQencryptPassword(StringValueCStr(password), StringValueCStr(username));
            rval = rb_str_new2( encrypted );
            PQfreemem( encrypted );

            OBJ_INFECT( rval, password );
            OBJ_INFECT( rval, username );

            return rval;
    }

escape_bytea( string ) → String click to toggle source

Escapes binary data for use within an SQL command with the type `bytea`.

Certain byte values must be escaped (but all byte values may be escaped) when used as part of a `bytea` literal in an SQL statement. In general, to escape a byte, it is converted into the three digit octal number equal to the octet value, and preceded by two backslashes. The single quote (') and backslash () characters have special alternative escape sequences. escape_bytea performs this operation, escaping only the minimally required bytes.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

    static VALUE
    pgconn_s_escape_bytea(VALUE self, VALUE str)
    {
            unsigned char *from, *to;
            size_t from_len, to_len;
            VALUE ret;

            Check_Type(str, T_STRING);
            from      = (unsigned char*)RSTRING_PTR(str);
            from_len  = RSTRING_LEN(str);

            if ( rb_obj_is_kind_of(self, rb_cPGconn) ) {
                    to = PQescapeByteaConn(pg_get_pgconn(self), from, from_len, &to_len);
            } else {
                    to = PQescapeBytea( from, from_len, &to_len);
            }

            ret = rb_str_new((char*)to, to_len - 1);
            OBJ_INFECT(ret, str);
            PQfreemem(to);
            return ret;
    }

escape_string( str ) → String click to toggle source

Returns a SQL-safe version of the String str. This is the preferred way to make strings safe for inclusion in SQL queries.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

Encoding of escaped string will be equal to client encoding of connection.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

    static VALUE
    pgconn_s_escape(VALUE self, VALUE string)
    {
            size_t size;
            int error;
            VALUE result;
            int enc_idx;
            int singleton = !rb_obj_is_kind_of(self, rb_cPGconn);

            StringValueCStr(string);
            enc_idx = ENCODING_GET( singleton ? string : self );
            if( ENCODING_GET(string) != enc_idx ){
                    string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
            }

            result = rb_str_new(NULL, RSTRING_LEN(string) * 2 + 1);
            PG_ENCODING_SET_NOCHECK(result, enc_idx);
            if( !singleton ) {
                    size = PQescapeStringConn(pg_get_pgconn(self), RSTRING_PTR(result),
                            RSTRING_PTR(string), RSTRING_LEN(string), &error);
                    if(error) {
                            rb_raise(rb_ePGerror, "%s", PQerrorMessage(pg_get_pgconn(self)));
                    }
            } else {
                    size = PQescapeString(RSTRING_PTR(result), RSTRING_PTR(string), RSTRING_LEN(string));
            }
            rb_str_set_len(result, size);
            OBJ_INFECT(result, string);

            return result;
    }

PG::Connection.new → conn click to toggle source
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn

Create a connection to the specified server.

`host`

  server hostname

`hostaddr`

  server address (avoids hostname lookup, overrides `host`)

`port`

  server port number

`dbname`

  connecting database name

`user`

  login user name

`password`

  login password

`connect_timeout`

  maximum time to wait for connection to succeed

`options`

  backend options

`tty`

  (ignored in newer versions of PostgreSQL)

`sslmode`

  (disable|allow|prefer|require)

`krbsrvname`

  kerberos service name

`gsslib`

  GSS library to use for GSSAPI authentication

`service`

  service name to use for additional parameters

Examples:

    # Connect using all defaults
    PG::Connection.new

    # As a Hash
    PG::Connection.new( :dbname => 'test', :port => 5432 )

    # As a String
    PG::Connection.new( "dbname=test port=5432" )

    # As an Array
    PG::Connection.new( nil, 5432, nil, nil, 'test', nil, nil )

If the Ruby default internal encoding is set (i.e., Encoding.default_internal != nil), the connection will have its `client_encoding` set accordingly.

Raises a PG::Error if the connection fails.

    static VALUE
    pgconn_init(int argc, VALUE *argv, VALUE self)
    {
            t_pg_connection *this;
            VALUE conninfo;
            VALUE error;

            this = pg_get_connection( self );
            conninfo = rb_funcall2( rb_cPGconn, rb_intern("parse_connect_args"), argc, argv );
            this->pgconn = gvl_PQconnectdb(StringValueCStr(conninfo));

            if(this->pgconn == NULL)
                    rb_raise(rb_ePGerror, "PQconnectdb() unable to allocate structure");

            if (PQstatus(this->pgconn) == CONNECTION_BAD) {
                    error = rb_exc_new2(rb_eConnectionBad, PQerrorMessage(this->pgconn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }

            pgconn_set_default_encoding( self );

            if (rb_block_given_p()) {
                    return rb_ensure(rb_yield, self, pgconn_finish, self);
            }
            return self;
    }

parse_connect_args( *args ) click to toggle source

Parse the connection `args` into a connection-parameter string. See ::new for valid arguments.

    # File lib/pg/connection.rb, line 34
    def self::parse_connect_args( *args )
            return '' if args.empty?

            hash_arg = args.last.is_a?( Hash ) ? args.pop : {}
            option_string = ''
            options = {}

            # Parameter 'fallback_application_name' was introduced in PostgreSQL 9.0
            # together with PQescapeLiteral().
            if PG::Connection.instance_methods.find {|m| m.to_sym == :escape_literal }
                    options[:fallback_application_name] = $0.sub( /^(.{30}).{4,}(.{30})$/ ){ $1+"..."+$2 }
            end

            if args.length == 1
                    case args.first
                    when URI, /\A#{URI.regexp}\z/
                            uri = URI(args.first)
                            options.merge!( Hash[URI.decode_www_form( uri.query )] ) if uri.query
                    when /=/
                            # Option string style
                            option_string = args.first.to_s
                    else
                            # Positional parameters
                            options[CONNECT_ARGUMENT_ORDER.first.to_sym] = args.first
                    end
            else
                    max = CONNECT_ARGUMENT_ORDER.length
                    raise ArgumentError,
                            "Extra positional parameter %d: %p" % [ max + 1, args[max] ] if args.length > max

                    CONNECT_ARGUMENT_ORDER.zip( args ) do |(k,v)|
                            options[ k.to_sym ] = v if v
                    end
            end

            options.merge!( hash_arg )

            if uri
                    uri.host     = nil if options[:host]
                    uri.port     = nil if options[:port]
                    uri.user     = nil if options[:user]
                    uri.password = nil if options[:password]
                    uri.path     = '' if options[:dbname]
                    uri.query    = URI.encode_www_form( options )
                    return uri.to_s.sub( /^#{uri.scheme}:(?!\/\/)/, "#{uri.scheme}://" )
            else
                    option_string += ' ' unless option_string.empty? && options.empty?
                    return option_string + options.map { |k,v| "#{k}=#{quote_connstr(v)}" }.join( ' ' )
            end
    end

PG::Connection.ping(connection_hash) → Integer click to toggle source
PG::Connection.ping(connection_string) → Integer
PG::Connection.ping(host, port, options, tty, dbname, login, password) → Integer

Check server status.

Returns one of:

`PQPING_OK`

  server is accepting connections

`PQPING_REJECT`

  server is alive but rejecting connections

`PQPING_NO_RESPONSE`

  could not establish connection

`PQPING_NO_ATTEMPT`

  connection not attempted (bad params)

Available since PostgreSQL-9.1

    static VALUE
    pgconn_s_ping( int argc, VALUE *argv, VALUE klass )
    {
            PGPing ping;
            VALUE conninfo;

            conninfo = rb_funcall2( klass, rb_intern("parse_connect_args"), argc, argv );
            ping     = PQping( StringValueCStr(conninfo) );

            return INT2FIX((int)ping);
    }

quote_connstr( value ) click to toggle source

Quote the given `value` for use in a connection-parameter string.

    # File lib/pg/connection.rb, line 27
    def self::quote_connstr( value )
            return "'" + value.to_s.gsub( /[\\']/ ) {|m| '\\' + m } + "'"
    end

quote_ident( str ) → String click to toggle source
quote_ident( array ) → String

Returns a string that is safe for inclusion in a SQL query as an identifier. Note: this is not a quote function for values, but for identifiers.

For example, in a typical SQL query: `SELECT FOO FROM MYTABLE` The identifier `FOO` is folded to lower case, so it actually means `foo`. If you really want to access the case-sensitive field name `FOO`, use this function like `conn.quote_ident('FOO')`, which will return `"FOO"` (with double-quotes). PostgreSQL will see the double-quotes, and it will not fold to lower case.

Similarly, this function also protects against special characters, and other things that might allow SQL injection if the identifier comes from an untrusted source.

If the parameter is an Array, then all it's values are separately quoted and then joined by a “.” character. This can be used for identifiers in the form “schema”.“table”.“column” .

This method is functional identical to the encoder PG::TextEncoder::Identifier .

If the instance method form is used and the input string character encoding is different to the connection encoding, then the string is converted to this encoding, so that the returned string is always encoded as #internal_encoding .

In the singleton form (PG::Connection.quote_ident) the character encoding of the result string is set to the character encoding of the input string.

    static VALUE
    pgconn_s_quote_ident(VALUE self, VALUE str_or_array)
    {
            VALUE ret;
            int enc_idx;

            if( rb_obj_is_kind_of(self, rb_cPGconn) ){
                    enc_idx = ENCODING_GET( self );
            }else{
                    enc_idx = RB_TYPE_P(str_or_array, T_STRING) ? ENCODING_GET( str_or_array ) : rb_ascii8bit_encindex();
            }
            pg_text_enc_identifier(NULL, str_or_array, NULL, &ret, enc_idx);

            OBJ_INFECT(ret, str_or_array);

            return ret;
    }

PG::Connection.unescape_bytea( string ) click to toggle source

Converts an escaped string representation of binary data into binary data — the reverse of escape_bytea. This is needed when retrieving `bytea` data in text format, but not when retrieving it in binary format.

    static VALUE
    pgconn_s_unescape_bytea(VALUE self, VALUE str)
    {
            unsigned char *from, *to;
            size_t to_len;
            VALUE ret;

            UNUSED( self );

            Check_Type(str, T_STRING);
            from = (unsigned char*)StringValueCStr(str);

            to = PQunescapeBytea(from, &to_len);

            ret = rb_str_new((char*)to, to_len);
            OBJ_INFECT(ret, str);
            PQfreemem(to);
            return ret;
    }

### Public Instance Methods

async_describe_portal( portal_name ) → PG::Result click to toggle source

This function has the same behavior as sync_describe_portal, but is implemented using the asynchronous command processing API of libpq. See async_exec for the differences between the two API variants.

    static VALUE
    pgconn_async_describe_portal(VALUE self, VALUE portal)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            pgconn_send_describe_portal( self, portal );
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

async_describe_prepared( statement_name ) → PG::Result click to toggle source

This function has the same behavior as sync_describe_prepared, but is implemented using the asynchronous command processing API of libpq. See async_exec for the differences between the two API variants.

    static VALUE
    pgconn_async_describe_prepared(VALUE self, VALUE stmt_name)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            pgconn_send_describe_prepared( self, stmt_name );
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

async_exec(sql) → PG::Result click to toggle source
async_exec(sql) {|pg_result| block }

This function has the same behavior as sync_exec, but is implemented using the asynchronous command processing API of libpq.

Both sync_exec and async_exec release the GVL while waiting for server response, so that concurrent threads will get executed. However async_exec has two advantages:

1. async_exec can be aborted by signals (like Ctrl-C), while exec blocks signal processing until the query is answered.

2. Ruby VM gets notified about IO blocked operations. It can therefore schedule thing like garbage collection, while queries are running like in this proposal: bugs.ruby-lang.org/issues/14723

    static VALUE
    pgconn_async_exec(int argc, VALUE *argv, VALUE self)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            pgconn_send_query( argc, argv, self );
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

Also aliased as: async_query
async_exec_params(sql, params [, result_format [, type_map ]] ) → nil click to toggle source
async_exec_params(sql, params [, result_format [, type_map ]] ) {|pg_result| block }

This function has the same behavior as sync_exec_params, but is implemented using the asynchronous command processing API of libpq. See async_exec for the differences between the two API variants.

    static VALUE
    pgconn_async_exec_params(int argc, VALUE *argv, VALUE self)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            /* If called with no or nil parameters, use PQsendQuery for compatibility */
            if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                    pg_deprecated(3, ("forwarding async_exec_params to async_exec is deprecated"));
                    pgconn_send_query( argc, argv, self );
            } else {
                    pgconn_send_query_params( argc, argv, self );
            }
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

async_exec_prepared(statement_name [, params, result_format[, type_map]] ) → PG::Result click to toggle source
async_exec_prepared(statement_name [, params, result_format[, type_map]] ) {|pg_result| block }

This function has the same behavior as sync_exec_prepared, but is implemented using the asynchronous command processing API of libpq. See async_exec for the differences between the two API variants.

    static VALUE
    pgconn_async_exec_prepared(int argc, VALUE *argv, VALUE self)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            pgconn_send_query_prepared( argc, argv, self );
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

async_prepare(stmt_name, sql [, param_types ] ) → PG::Result click to toggle source

This function has the same behavior as sync_prepare, but is implemented using the asynchronous command processing API of libpq. See async_exec for the differences between the two API variants.

    static VALUE
    pgconn_async_prepare(int argc, VALUE *argv, VALUE self)
    {
            VALUE rb_pgresult = Qnil;

            pgconn_discard_results( self );
            pgconn_send_prepare( argc, argv, self );
            pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
            rb_pgresult = pgconn_get_last_result( self );

            if ( rb_block_given_p() ) {
                    return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
            }
            return rb_pgresult;
    }

async_query(*args)
Alias for: async_exec
backend_pid() → Integer click to toggle source

Returns the process ID of the backend server process for this connection. Note that this is a PID on database server host.

    static VALUE
    pgconn_backend_pid(VALUE self)
    {
            return INT2NUM(PQbackendPID(pg_get_pgconn(self)));
    }

block( [ timeout ] ) → Boolean click to toggle source

Blocks until the server is no longer busy, or until the optional timeout is reached, whichever comes first. timeout is measured in seconds and can be fractional.

Returns `false` if timeout is reached, `true` otherwise.

If `true` is returned, `conn.is_busy` will return `false` and `conn.get_result` will not block.

    static VALUE
    pgconn_block( int argc, VALUE *argv, VALUE self ) {
            PGconn *conn = pg_get_pgconn( self );

            struct timeval timeout;
            struct timeval *ptimeout = NULL;
            VALUE timeout_in;
            double timeout_sec;
            void *ret;

            if ( rb_scan_args(argc, argv, "01", &timeout_in) == 1 ) {
                    timeout_sec = NUM2DBL( timeout_in );
                    timeout.tv_sec = (time_t)timeout_sec;
                    timeout.tv_usec = (suseconds_t)((timeout_sec - (long)timeout_sec) * 1e6);
                    ptimeout = &timeout;
            }

            ret = wait_socket_readable( conn, ptimeout, get_result_readable);

            if( !ret )
                    return Qfalse;

            return Qtrue;
    }

cancel() → String click to toggle source

Requests cancellation of the command currently being processed. (Only implemented in PostgreSQL >= 8.0)

Returns `nil` on success, or a string containing the error message if a failure occurs.

    static VALUE
    pgconn_cancel(VALUE self)
    {
            char errbuf[256];
            PGcancel *cancel;
            VALUE retval;
            int ret;

            cancel = PQgetCancel(pg_get_pgconn(self));
            if(cancel == NULL)
                    rb_raise(rb_ePGerror,"Invalid connection!");

            ret = gvl_PQcancel(cancel, errbuf, 256);
            if(ret == 1)
                    retval = Qnil;
            else
                    retval = rb_str_new2(errbuf);

            PQfreeCancel(cancel);
            return retval;
    }

client_encoding=(p1)
Alias for: set_client_encoding
close()
Alias for: finish
conndefaults() click to toggle source

Returns an array of Hashes with connection defaults. See ::conndefaults for details.

    # File lib/pg/connection.rb, line 218
    def conndefaults
            return self.class.conndefaults
    end

conndefaults_hash() click to toggle source

Returns a Hash with connection defaults. See ::conndefaults_hash for details.

    # File lib/pg/connection.rb, line 234
    def conndefaults_hash
            return self.class.conndefaults_hash
    end

connect_poll() → Integer click to toggle source

Returns one of:

`PGRES_POLLING_READING`

  wait until the socket is ready to read

`PGRES_POLLING_WRITING`

  wait until the socket is ready to write

`PGRES_POLLING_FAILED`

  the asynchronous connection has failed

`PGRES_POLLING_OK`

  the asynchronous connection is ready

Example:

    conn = PG::Connection.connect_start("dbname=mydatabase")
    socket = conn.socket_io
    status = conn.connect_poll
    while(status != PG::PGRES_POLLING_OK) do
      # do some work while waiting for the connection to complete
      if(status == PG::PGRES_POLLING_READING)
        if(not select([socket], [], [], 10.0))
          raise "Asynchronous connection timed out!"
        end
      elsif(status == PG::PGRES_POLLING_WRITING)
        if(not select([], [socket], [], 10.0))
          raise "Asynchronous connection timed out!"
        end
      end
      status = conn.connect_poll
    end
    # now conn.status == CONNECTION_OK, and connection
    # is ready.

    static VALUE
    pgconn_connect_poll(VALUE self)
    {
            PostgresPollingStatusType status;
            status = gvl_PQconnectPoll(pg_get_pgconn(self));
            return INT2FIX((int)status);
    }

connection_needs_password() → Boolean click to toggle source

Returns `true` if the authentication method required a password, but none was available. `false` otherwise.

    static VALUE
    pgconn_connection_needs_password(VALUE self)
    {
            return PQconnectionNeedsPassword(pg_get_pgconn(self)) ? Qtrue : Qfalse;
    }

connection_used_password() → Boolean click to toggle source

Returns `true` if the authentication method used a caller-supplied password, `false` otherwise.

    static VALUE
    pgconn_connection_used_password(VALUE self)
    {
            return PQconnectionUsedPassword(pg_get_pgconn(self)) ? Qtrue : Qfalse;
    }

conninfo → hash click to toggle source

Returns the connection options used by a live connection.

Available since PostgreSQL-9.3

    static VALUE
    pgconn_conninfo( VALUE self )
    {
            PGconn *conn = pg_get_pgconn(self);
            PQconninfoOption *options = PQconninfo( conn );
            VALUE array = pgconn_make_conninfo_array( options );

            PQconninfoFree(options);

            return array;
    }

conninfo_hash() click to toggle source

Return the Postgres connection info structure as a Hash keyed by option keyword (as a Symbol).

See also conninfo

    # File lib/pg/connection.rb, line 245
    def conninfo_hash
            return self.conninfo.each_with_object({}) do |info, hash|
                    hash[ info[:keyword].to_sym ] = info[:val]
            end
    end

consume_input() click to toggle source

If input is available from the server, consume it. After calling `consume_input`, you can check `is_busy` or notifies to see if the state has changed.

    static VALUE
    pgconn_consume_input(self)
            VALUE self;
    {
            VALUE error;
            PGconn *conn = pg_get_pgconn(self);
            /* returns 0 on error */
            if(PQconsumeInput(conn) == 0) {
                    error = rb_exc_new2(rb_eConnectionBad, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

copy_data( sql [, coder] ) {|sql_result| ... } → PG::Result click to toggle source

Execute a copy process for transfering data to or from the server.

This issues the SQL COPY command via exec. The response to this (if there is no error in the command) is a PG::Result object that is passed to the block, bearing a status code of PGRES_COPY_OUT or PGRES_COPY_IN (depending on the specified copy direction). The application should then use put_copy_data or get_copy_data to receive or transmit data rows and should return from the block when finished.

copy_data returns another PG::Result object when the data transfer is complete. An exception is raised if some problem was encountered, so it isn't required to make use of any of them. At this point further SQL commands can be issued via exec. (It is not possible to execute other SQL commands using the same connection while the COPY operation is in progress.)

This method ensures, that the copy process is properly terminated in case of client side or server side failures. Therefore, in case of blocking mode of operation, copy_data is preferred to raw calls of put_copy_data, get_copy_data and put_copy_end.

coder can be a PG::Coder derivation (typically PG::TextEncoder::CopyRow or PG::TextDecoder::CopyRow). This enables encoding of data fields given to put_copy_data or decoding of fields received by get_copy_data.

Example with CSV input format:

    conn.exec "create table my_table (a text,b text,c text,d text)"
    conn.copy_data "COPY my_table FROM STDIN CSV" do
      conn.put_copy_data "some,data,to,copy\n"
      conn.put_copy_data "more,data,to,copy\n"
    end

This creates `my_table` and inserts two CSV rows.

The same with text format encoder PG::TextEncoder::CopyRow and Array input:

    enco = PG::TextEncoder::CopyRow.new
    conn.copy_data "COPY my_table FROM STDIN", enco do
      conn.put_copy_data ['some', 'data', 'to', 'copy']
      conn.put_copy_data ['more', 'data', 'to', 'copy']
    end

Example with CSV output format:

    conn.copy_data "COPY my_table TO STDOUT CSV" do
      while row=conn.get_copy_data
        p row
      end
    end

This prints all rows of `my_table` to stdout:

    "some,data,to,copy\n"
    "more,data,to,copy\n"

The same with text format decoder PG::TextDecoder::CopyRow and Array output:

    deco = PG::TextDecoder::CopyRow.new
    conn.copy_data "COPY my_table TO STDOUT", deco do
      while row=conn.get_copy_data
        p row
      end
    end

This receives all rows of `my_table` as ruby array:

    ["some", "data", "to", "copy"]
    ["more", "data", "to", "copy"]

    # File lib/pg/connection.rb, line 154
    def copy_data( sql, coder=nil )
            res = exec( sql )

            case res.result_status
            when PGRES_COPY_IN
                    begin
                            if coder
                                    old_coder = self.encoder_for_put_copy_data
                                    self.encoder_for_put_copy_data = coder
                            end
                            yield res
                    rescue Exception => err
                            errmsg = "%s while copy data: %s" % [ err.class.name, err.message ]
                            put_copy_end( errmsg )
                            get_result
                            raise
                    else
                            put_copy_end
                            get_last_result
                    ensure
                            self.encoder_for_put_copy_data = old_coder if coder
                    end

            when PGRES_COPY_OUT
                    begin
                            if coder
                                    old_coder = self.decoder_for_get_copy_data
                                    self.decoder_for_get_copy_data = coder
                            end
                            yield res
                    rescue Exception => err
                            cancel
                            while get_copy_data
                            end
                            while get_result
                            end
                            raise
                    else
                            res = get_last_result
                            if !res || res.result_status != PGRES_COMMAND_OK
                                    while get_copy_data
                                    end
                                    while get_result
                                    end
                                    raise PG::NotAllCopyDataRetrieved, "Not all COPY data retrieved"
                            end
                            res
                    ensure
                            self.decoder_for_get_copy_data = old_coder if coder
                    end

            else
                    raise ArgumentError, "SQL command is no COPY statement: #{sql}"
            end
    end

db() click to toggle source

Returns the connected database name.

    static VALUE
    pgconn_db(VALUE self)
    {
            char *db = PQdb(pg_get_pgconn(self));
            if (!db) return Qnil;
            return rb_tainted_str_new2(db);
    }

decoder_for_get_copy_data → PG::Coder click to toggle source

Returns the default coder object that is currently set for type casting of received data by get_copy_data .

Returns either:

- a kind of PG::Coder

- `nil` - type encoding is disabled, returned data will be a String.

    static VALUE
    pgconn_decoder_for_get_copy_data_get(VALUE self)
    {
            t_pg_connection *this = pg_get_connection( self );

            return this->decoder_for_get_copy_data;
    }

decoder_for_get_copy_data = decoder click to toggle source

Set the default coder that is used for type casting of received data by get_copy_data .

`decoder` can be:

- a kind of PG::Coder

- `nil` - disable type decoding, returned data will be a String.

    static VALUE
    pgconn_decoder_for_get_copy_data_set(VALUE self, VALUE typemap)
    {
            t_pg_connection *this = pg_get_connection( self );

            if( typemap != Qnil ){
                    if ( !rb_obj_is_kind_of(typemap, rb_cPG_Coder) ) {
                            rb_raise( rb_eTypeError, "wrong argument type %s (expected kind of PG::Coder)",
                                            rb_obj_classname( typemap ) );
                    }
                    Check_Type(typemap, T_DATA);
            }
            this->decoder_for_get_copy_data = typemap;

            return typemap;
    }

discard_results() click to toggle source

Silently discard any prior query result that application didn't eat. This is done prior of Connection#exec and sibling methods and can be called explicitly when using the async API.

    static VALUE
    pgconn_discard_results(VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);

            PGresult *cur;
            while ((cur = gvl_PQgetResult(conn)) != NULL) {
                    int status = PQresultStatus(cur);
                    PQclear(cur);
                    if (status == PGRES_COPY_IN){
                            gvl_PQputCopyEnd(conn, "COPY terminated by new PQexec");
                    }
                    if (status == PGRES_COPY_OUT){
                            char *buffer = NULL;
                            while( gvl_PQgetCopyData(conn, &buffer, 0) > 0)
                                    PQfreemem(buffer);
                    }
            }

            return Qnil;
    }

encoder_for_put_copy_data → PG::Coder click to toggle source

Returns the default coder object that is currently set for type casting of parameters to put_copy_data .

Returns either:

- a kind of PG::Coder

- `nil` - type encoding is disabled, data must be a String.

    static VALUE
    pgconn_encoder_for_put_copy_data_get(VALUE self)
    {
            t_pg_connection *this = pg_get_connection( self );

            return this->encoder_for_put_copy_data;
    }

encoder_for_put_copy_data = encoder click to toggle source

Set the default coder that is used for type casting of parameters to put_copy_data .

`encoder` can be:

- a kind of PG::Coder

- `nil` - disable type encoding, data must be a String.

    static VALUE
    pgconn_encoder_for_put_copy_data_set(VALUE self, VALUE typemap)
    {
            t_pg_connection *this = pg_get_connection( self );

            if( typemap != Qnil ){
                    if ( !rb_obj_is_kind_of(typemap, rb_cPG_Coder) ) {
                            rb_raise( rb_eTypeError, "wrong argument type %s (expected kind of PG::Coder)",
                                            rb_obj_classname( typemap ) );
                    }
                    Check_Type(typemap, T_DATA);
            }
            this->encoder_for_put_copy_data = typemap;

            return typemap;
    }

encrypt_password( password, username, algorithm=nil ) → String click to toggle source

This function is intended to be used by client applications that wish to send commands like `ALTER USER joe PASSWORD 'pwd'`. It is good practice not to send the original cleartext password in such a command, because it might be exposed in command logs, activity displays, and so on. Instead, use this function to convert the password to encrypted form before it is sent.

The `password` and `username` arguments are the cleartext password, and the SQL name of the user it is for. `algorithm` specifies the encryption algorithm to use to encrypt the password. Currently supported algorithms are `md5` and `scram-sha-256` (`on` and `off` are also accepted as aliases for `md5`, for compatibility with older server versions). Note that support for `scram-sha-256` was introduced in PostgreSQL version 10, and will not work correctly with older server versions. If algorithm is omitted or `nil`, this function will query the server for the current value of the `password_encryption` setting. That can block, and will fail if the current transaction is aborted, or if the connection is busy executing another query. If you wish to use the default algorithm for the server but want to avoid blocking, query `password_encryption` yourself before calling encrypt_password, and pass that value as the algorithm.

Return value is the encrypted password. The caller can assume the string doesn't contain any special characters that would require escaping.

Available since PostgreSQL-10

    static VALUE
    pgconn_encrypt_password(int argc, VALUE *argv, VALUE self)
    {
            char *encrypted = NULL;
            VALUE rval = Qnil;
            VALUE password, username, algorithm;
            PGconn *conn = pg_get_pgconn(self);

            rb_scan_args( argc, argv, "21", &password, &username, &algorithm );

            Check_Type(password, T_STRING);
            Check_Type(username, T_STRING);

            encrypted = gvl_PQencryptPasswordConn(conn, StringValueCStr(password), StringValueCStr(username), RTEST(algorithm) ? StringValueCStr(algorithm) : NULL);
            if ( encrypted ) {
                    rval = rb_str_new2( encrypted );
                    PQfreemem( encrypted );

                    OBJ_INFECT( rval, password );
                    OBJ_INFECT( rval, username );
                    OBJ_INFECT( rval, algorithm );
            } else {
                    rb_raise(rb_ePGerror, "%s", PQerrorMessage(conn));
            }

            return rval;
    }

error_message → String click to toggle source

Returns the error message about connection.

    static VALUE
    pgconn_error_message(VALUE self)
    {
            char *error = PQerrorMessage(pg_get_pgconn(self));
            if (!error) return Qnil;
            return rb_tainted_str_new2(error);
    }

escape(p1)
Alias for: escape_string
escape_bytea( string ) → String click to toggle source

Escapes binary data for use within an SQL command with the type `bytea`.

Certain byte values must be escaped (but all byte values may be escaped) when used as part of a `bytea` literal in an SQL statement. In general, to escape a byte, it is converted into the three digit octal number equal to the octet value, and preceded by two backslashes. The single quote (') and backslash () characters have special alternative escape sequences. escape_bytea performs this operation, escaping only the minimally required bytes.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

    static VALUE
    pgconn_s_escape_bytea(VALUE self, VALUE str)
    {
            unsigned char *from, *to;
            size_t from_len, to_len;
            VALUE ret;

            Check_Type(str, T_STRING);
            from      = (unsigned char*)RSTRING_PTR(str);
            from_len  = RSTRING_LEN(str);

            if ( rb_obj_is_kind_of(self, rb_cPGconn) ) {
                    to = PQescapeByteaConn(pg_get_pgconn(self), from, from_len, &to_len);
            } else {
                    to = PQescapeBytea( from, from_len, &to_len);
            }

            ret = rb_str_new((char*)to, to_len - 1);
            OBJ_INFECT(ret, str);
            PQfreemem(to);
            return ret;
    }

escape_identifier( str ) → String click to toggle source

Escape an arbitrary String `str` as an identifier.

This method does the same as quote_ident with a String argument, but it doesn't support an Array argument and it makes use of libpq to process the string.

Available since PostgreSQL-9.0

    static VALUE
    pgconn_escape_identifier(VALUE self, VALUE string)
    {
            PGconn *conn = pg_get_pgconn(self);
            char *escaped = NULL;
            VALUE error;
            VALUE result = Qnil;
            int enc_idx = ENCODING_GET(self);

            StringValueCStr(string);
            if( ENCODING_GET(string) != enc_idx ){
                    string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
            }

            escaped = PQescapeIdentifier(conn, RSTRING_PTR(string), RSTRING_LEN(string));
            if (escaped == NULL)
            {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
                    return Qnil;
            }
            result = rb_str_new2(escaped);
            PQfreemem(escaped);
            OBJ_INFECT(result, string);
            PG_ENCODING_SET_NOCHECK(result, enc_idx);

            return result;
    }

escape_literal( str ) → String click to toggle source

Escape an arbitrary String `str` as a literal.

Available since PostgreSQL-9.0

    static VALUE
    pgconn_escape_literal(VALUE self, VALUE string)
    {
            PGconn *conn = pg_get_pgconn(self);
            char *escaped = NULL;
            VALUE error;
            VALUE result = Qnil;
            int enc_idx = ENCODING_GET(self);

            StringValueCStr(string);
            if( ENCODING_GET(string) != enc_idx ){
                    string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
            }

            escaped = PQescapeLiteral(conn, RSTRING_PTR(string), RSTRING_LEN(string));
            if (escaped == NULL)
            {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
                    return Qnil;
            }
            result = rb_str_new2(escaped);
            PQfreemem(escaped);
            OBJ_INFECT(result, string);
            PG_ENCODING_SET_NOCHECK(result, enc_idx);

            return result;
    }

escape_string( str ) → String click to toggle source

Returns a SQL-safe version of the String str. This is the preferred way to make strings safe for inclusion in SQL queries.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

Encoding of escaped string will be equal to client encoding of connection.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

    static VALUE
    pgconn_s_escape(VALUE self, VALUE string)
    {
            size_t size;
            int error;
            VALUE result;
            int enc_idx;
            int singleton = !rb_obj_is_kind_of(self, rb_cPGconn);

            StringValueCStr(string);
            enc_idx = ENCODING_GET( singleton ? string : self );
            if( ENCODING_GET(string) != enc_idx ){
                    string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
            }

            result = rb_str_new(NULL, RSTRING_LEN(string) * 2 + 1);
            PG_ENCODING_SET_NOCHECK(result, enc_idx);
            if( !singleton ) {
                    size = PQescapeStringConn(pg_get_pgconn(self), RSTRING_PTR(result),
                            RSTRING_PTR(string), RSTRING_LEN(string), &error);
                    if(error) {
                            rb_raise(rb_ePGerror, "%s", PQerrorMessage(pg_get_pgconn(self)));
                    }
            } else {
                    size = PQescapeString(RSTRING_PTR(result), RSTRING_PTR(string), RSTRING_LEN(string));
            }
            rb_str_set_len(result, size);
            OBJ_INFECT(result, string);

            return result;
    }

Also aliased as: escape
external_encoding() → Encoding click to toggle source

Return the `server_encoding` of the connected database as a Ruby Encoding object. The `SQL_ASCII` encoding is mapped to to `ASCII_8BIT`.

    static VALUE
    pgconn_external_encoding(VALUE self)
    {
            t_pg_connection *this = pg_get_connection_safe( self );
            rb_encoding *enc = NULL;
            const char *pg_encname = NULL;

            /* Use cached value if found */
            if ( RTEST(this->external_encoding) ) return this->external_encoding;

            pg_encname = PQparameterStatus( this->pgconn, "server_encoding" );
            enc = pg_get_pg_encname_as_rb_encoding( pg_encname );
            this->external_encoding = rb_enc_from_encoding( enc );

            return this->external_encoding;
    }

finish click to toggle source

Closes the backend connection.

    static VALUE
    pgconn_finish( VALUE self )
    {
            t_pg_connection *this = pg_get_connection_safe( self );

            pgconn_close_socket_io( self );
            PQfinish( this->pgconn );
            this->pgconn = NULL;
            return Qnil;
    }

Also aliased as: close
finished? → boolean click to toggle source

Returns `true` if the backend connection has been closed.

    static VALUE
    pgconn_finished_p( VALUE self )
    {
            t_pg_connection *this = pg_get_connection( self );
            if ( this->pgconn ) return Qfalse;
            return Qtrue;
    }

flush() → Boolean click to toggle source

Attempts to flush any queued output data to the server. Returns `true` if data is successfully flushed, `false` if not (can only return `false` if connection is nonblocking. Raises PG::Error if some other failure occurred.

    static VALUE
    pgconn_flush(self)
            VALUE self;
    {
            PGconn *conn = pg_get_pgconn(self);
            int ret;
            VALUE error;
            ret = PQflush(conn);
            if(ret == -1) {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return (ret) ? Qfalse : Qtrue;
    }

get_client_encoding() → String click to toggle source

Returns the client encoding as a String.

    static VALUE
    pgconn_get_client_encoding(VALUE self)
    {
            char *encoding = (char *)pg_encoding_to_char(PQclientEncoding(pg_get_pgconn(self)));
            return rb_tainted_str_new2(encoding);
    }

get_copy_data( [ async = false [, decoder = nil ]] ) → Object click to toggle source

Return one row of data, `nil` if the copy is done, or `false` if the call would block (only possible if async is true).

If decoder is not set or `nil`, data is returned as binary string.

If decoder is set to a PG::Coder derivation, the return type depends on this decoder. PG::TextDecoder::CopyRow decodes the received data fields from one row of PostgreSQL's COPY text format to an Array of Strings. Optionally the decoder can type cast the single fields to various Ruby types in one step, if PG::CopyCoder#type_map is set accordingly.

See also copy_data.

    static VALUE
    pgconn_get_copy_data(int argc, VALUE *argv, VALUE self )
    {
            VALUE async_in;
            VALUE error;
            VALUE result;
            int ret;
            char *buffer;
            VALUE decoder;
            t_pg_coder *p_coder = NULL;
            t_pg_connection *this = pg_get_connection_safe( self );

            rb_scan_args(argc, argv, "02", &async_in, &decoder);

            if( NIL_P(decoder) ){
                    if( !NIL_P(this->decoder_for_get_copy_data) ){
                            p_coder = DATA_PTR( this->decoder_for_get_copy_data );
                    }
            } else if( rb_obj_is_kind_of(decoder, rb_cPG_Coder) ) {
                    Data_Get_Struct( decoder, t_pg_coder, p_coder );
            } else {
                    rb_raise( rb_eTypeError, "wrong decoder type %s (expected some kind of PG::Coder)",
                                    rb_obj_classname( decoder ) );
            }

            ret = gvl_PQgetCopyData(this->pgconn, &buffer, RTEST(async_in));
            if(ret == -2) { /* error */
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(this->pgconn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            if(ret == -1) { /* No data left */
                    return Qnil;
            }
            if(ret == 0) { /* would block */
                    return Qfalse;
            }

            if( p_coder ){
                    t_pg_coder_dec_func dec_func = pg_coder_dec_func( p_coder, p_coder->format );
                    result =  dec_func( p_coder, buffer, ret, 0, 0, ENCODING_GET(self) );
            } else {
                    result = rb_tainted_str_new(buffer, ret);
            }

            PQfreemem(buffer);
            return result;
    }

get_last_result( ) → PG::Result click to toggle source

This function retrieves all available results on the current connection (from previously issued asynchronous commands like +send_query()+) and returns the last non-NULL result, or `nil` if no results are available.

This function is similar to get_result except that it is designed to get one and only one result.

    static VALUE
    pgconn_get_last_result(VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            VALUE rb_pgresult = Qnil;
            PGresult *cur, *prev;

            cur = prev = NULL;
            while ((cur = gvl_PQgetResult(conn)) != NULL) {
                    int status;

                    if (prev) PQclear(prev);
                    prev = cur;

                    status = PQresultStatus(cur);
                    if (status == PGRES_COPY_OUT || status == PGRES_COPY_IN)
                            break;
            }

            if (prev) {
                    rb_pgresult = pg_new_result( prev, self );
                    pg_result_check(rb_pgresult);
            }

            return rb_pgresult;
    }

get_result() → PG::Result click to toggle source
get_result() {|pg_result| block }

Blocks waiting for the next result from a call to send_query (or another asynchronous command), and returns it. Returns `nil` if no more results are available.

Note: call this function repeatedly until it returns `nil`, or else you will not be able to issue further commands.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, `conn.exec` returns the value of the block.

    static VALUE
    pgconn_get_result(VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result;
            VALUE rb_pgresult;

            result = gvl_PQgetResult(conn);
            if(result == NULL)
                    return Qnil;
            rb_pgresult = pg_new_result(result, self);
            if (rb_block_given_p()) {
                    return rb_ensure(rb_yield, rb_pgresult,
                            pg_result_clear, rb_pgresult);
            }
            return rb_pgresult;
    }

guess_result_memsize = enabled click to toggle source

This method is for testing only and will probably be removed in the future.

    static VALUE
    pgconn_guess_result_memsize_set(VALUE self, VALUE enable)
    {
            t_pg_connection *this = pg_get_connection( self );
            this->guess_result_memsize = RTEST(enable);
            return enable;
    }

host() click to toggle source

Returns the connected server name.

    static VALUE
    pgconn_host(VALUE self)
    {
            char *host = PQhost(pg_get_pgconn(self));
            if (!host) return Qnil;
            return rb_tainted_str_new2(host);
    }

internal_encoding → Encoding click to toggle source

defined in Ruby 1.9 or later.

Returns:

- an Encoding - client_encoding of the connection as a Ruby Encoding object.

- nil - the client_encoding is 'SQL_ASCII'

    static VALUE
    pgconn_internal_encoding(VALUE self)
    {
            PGconn *conn = pg_get_pgconn( self );
            rb_encoding *enc = pg_conn_enc_get( conn );

            if ( enc ) {
                    return rb_enc_from_encoding( enc );
            } else {
                    return Qnil;
            }
    }

internal_encoding = value click to toggle source

A wrapper of set_client_encoding. defined in Ruby 1.9 or later.

`value` can be one of:

- an Encoding

- a String - a name of Encoding

- `nil` - sets the client_encoding to SQL_ASCII.

    static VALUE
    pgconn_internal_encoding_set(VALUE self, VALUE enc)
    {
            VALUE enc_inspect;
            if (NIL_P(enc)) {
                    pgconn_set_client_encoding( self, rb_usascii_str_new_cstr("SQL_ASCII") );
                    return enc;
            }
            else if ( TYPE(enc) == T_STRING && strcasecmp("JOHAB", StringValueCStr(enc)) == 0 ) {
                    pgconn_set_client_encoding(self, rb_usascii_str_new_cstr("JOHAB"));
                    return enc;
            }
            else {
                    rb_encoding *rbenc = rb_to_encoding( enc );
                    const char *name = pg_get_rb_encoding_as_pg_encoding( rbenc );

                    if ( gvl_PQsetClientEncoding(pg_get_pgconn( self ), name) == -1 ) {
                            VALUE server_encoding = pgconn_external_encoding( self );
                            rb_raise( rb_eEncCompatError, "incompatible character encodings: %s and %s",
                                              rb_enc_name(rb_to_encoding(server_encoding)), name );
                    }
                    pgconn_set_internal_encoding_index( self );
                    return enc;
            }

            enc_inspect = rb_inspect(enc);
            rb_raise( rb_ePGerror, "unknown encoding: %s", StringValueCStr(enc_inspect) );

            return Qnil;
    }

is_busy() → Boolean click to toggle source

Returns `true` if a command is busy, that is, if PQgetResult would block. Otherwise returns `false`.

    static VALUE
    pgconn_is_busy(self)
            VALUE self;
    {
            return gvl_PQisBusy(pg_get_pgconn(self)) ? Qtrue : Qfalse;
    }

isnonblocking() → Boolean click to toggle source

Returns `true` if a command is busy, that is, if PQgetResult would block. Otherwise returns `false`.

    static VALUE
    pgconn_isnonblocking(self)
            VALUE self;
    {
            return PQisnonblocking(pg_get_pgconn(self)) ? Qtrue : Qfalse;
    }

Also aliased as: nonblocking?
lo_close( lo_desc ) → nil click to toggle source

Closes the postgres large object of lo_desc.

    static VALUE
    pgconn_loclose(VALUE self, VALUE in_lo_desc)
    {
            PGconn *conn = pg_get_pgconn(self);
            int lo_desc = NUM2INT(in_lo_desc);

            if(lo_close(conn,lo_desc) < 0)
                    rb_raise(rb_ePGerror,"lo_close failed");

            return Qnil;
    }

Also aliased as: loclose
lo_creat( [mode] ) → Integer click to toggle source

Creates a large object with mode mode. Returns a large object Oid. On failure, it raises PG::Error.

    static VALUE
    pgconn_locreat(int argc, VALUE *argv, VALUE self)
    {
            Oid lo_oid;
            int mode;
            VALUE nmode;
            PGconn *conn = pg_get_pgconn(self);

            if (rb_scan_args(argc, argv, "01", &nmode) == 0)
                    mode = INV_READ;
            else
                    mode = NUM2INT(nmode);

            lo_oid = lo_creat(conn, mode);
            if (lo_oid == 0)
                    rb_raise(rb_ePGerror, "lo_creat failed");

            return UINT2NUM(lo_oid);
    }

Also aliased as: locreat
lo_create( oid ) → Integer click to toggle source

Creates a large object with oid oid. Returns the large object Oid. On failure, it raises PG::Error.

    static VALUE
    pgconn_locreate(VALUE self, VALUE in_lo_oid)
    {
            Oid ret, lo_oid;
            PGconn *conn = pg_get_pgconn(self);
            lo_oid = NUM2UINT(in_lo_oid);

            ret = lo_create(conn, lo_oid);
            if (ret == InvalidOid)
                    rb_raise(rb_ePGerror, "lo_create failed");

            return UINT2NUM(ret);
    }

Also aliased as: locreate
lo_export( oid, file ) → nil click to toggle source

Saves a large object of oid to a file.

    static VALUE
    pgconn_loexport(VALUE self, VALUE lo_oid, VALUE filename)
    {
            PGconn *conn = pg_get_pgconn(self);
            Oid oid;
            Check_Type(filename, T_STRING);

            oid = NUM2UINT(lo_oid);

            if (lo_export(conn, oid, StringValueCStr(filename)) < 0) {
                    rb_raise(rb_ePGerror, "%s", PQerrorMessage(conn));
            }
            return Qnil;
    }

Also aliased as: loexport
lo_import(file) → Integer click to toggle source

Import a file to a large object. Returns a large object Oid.

On failure, it raises a PG::Error.

    static VALUE
    pgconn_loimport(VALUE self, VALUE filename)
    {
            Oid lo_oid;

            PGconn *conn = pg_get_pgconn(self);

            Check_Type(filename, T_STRING);

            lo_oid = lo_import(conn, StringValueCStr(filename));
            if (lo_oid == 0) {
                    rb_raise(rb_ePGerror, "%s", PQerrorMessage(conn));
            }
            return UINT2NUM(lo_oid);
    }

Also aliased as: loimport
lo_lseek( lo_desc, offset, whence ) → Integer click to toggle source

Move the large object pointer lo_desc to offset offset. Valid values for whence are `SEEK_SET`, `SEEK_CUR`, and `SEEK_END`. (Or 0, 1, or 2.)

    static VALUE
    pgconn_lolseek(VALUE self, VALUE in_lo_desc, VALUE offset, VALUE whence)
    {
            PGconn *conn = pg_get_pgconn(self);
            int lo_desc = NUM2INT(in_lo_desc);
            int ret;

            if((ret = lo_lseek(conn, lo_desc, NUM2INT(offset), NUM2INT(whence))) < 0) {
                    rb_raise(rb_ePGerror, "lo_lseek failed");
            }

            return INT2FIX(ret);
    }

Also aliased as: lolseek, lo_seek, loseek
lo_open( oid, [mode] ) → Integer click to toggle source

Open a large object of oid. Returns a large object descriptor instance on success. The mode argument specifies the mode for the opened large object,which is either `INV_READ`, or `INV_WRITE`.

If mode is omitted, the default is `INV_READ`.

    static VALUE
    pgconn_loopen(int argc, VALUE *argv, VALUE self)
    {
            Oid lo_oid;
            int fd, mode;
            VALUE nmode, selfid;
            PGconn *conn = pg_get_pgconn(self);

            rb_scan_args(argc, argv, "11", &selfid, &nmode);
            lo_oid = NUM2UINT(selfid);
            if(NIL_P(nmode))
                    mode = INV_READ;
            else
                    mode = NUM2INT(nmode);

            if((fd = lo_open(conn, lo_oid, mode)) < 0) {
                    rb_raise(rb_ePGerror, "can't open large object: %s", PQerrorMessage(conn));
            }
            return INT2FIX(fd);
    }

Also aliased as: loopen
lo_read( lo_desc, len ) → String click to toggle source

Attempts to read len bytes from large object lo_desc, returns resulting data.

    static VALUE
    pgconn_loread(VALUE self, VALUE in_lo_desc, VALUE in_len)
    {
            int ret;
      PGconn *conn = pg_get_pgconn(self);
            int len = NUM2INT(in_len);
            int lo_desc = NUM2INT(in_lo_desc);
            VALUE str;
            char *buffer;

      buffer = ALLOC_N(char, len);
            if(buffer == NULL)
                    rb_raise(rb_eNoMemError, "ALLOC failed!");

            if (len < 0){
                    rb_raise(rb_ePGerror,"nagative length %d given", len);
            }

            if((ret = lo_read(conn, lo_desc, buffer, len)) < 0)
                    rb_raise(rb_ePGerror, "lo_read failed");

            if(ret == 0) {
                    xfree(buffer);
                    return Qnil;
            }

            str = rb_tainted_str_new(buffer, ret);
            xfree(buffer);

            return str;
    }

Also aliased as: loread
lo_seek(p1, p2, p3)
Alias for: lo_lseek
lo_tell( lo_desc ) → Integer click to toggle source

Returns the current position of the large object lo_desc.

    static VALUE
    pgconn_lotell(VALUE self, VALUE in_lo_desc)
    {
            int position;
            PGconn *conn = pg_get_pgconn(self);
            int lo_desc = NUM2INT(in_lo_desc);

            if((position = lo_tell(conn, lo_desc)) < 0)
                    rb_raise(rb_ePGerror,"lo_tell failed");

            return INT2FIX(position);
    }

Also aliased as: lotell
lo_truncate( lo_desc, len ) → nil click to toggle source

Truncates the large object lo_desc to size len.

    static VALUE
    pgconn_lotruncate(VALUE self, VALUE in_lo_desc, VALUE in_len)
    {
            PGconn *conn = pg_get_pgconn(self);
            int lo_desc = NUM2INT(in_lo_desc);
            size_t len = NUM2INT(in_len);

            if(lo_truncate(conn,lo_desc,len) < 0)
                    rb_raise(rb_ePGerror,"lo_truncate failed");

            return Qnil;
    }

Also aliased as: lotruncate
lo_unlink( oid ) → nil click to toggle source

Unlinks (deletes) the postgres large object of oid.

    static VALUE
    pgconn_lounlink(VALUE self, VALUE in_oid)
    {
            PGconn *conn = pg_get_pgconn(self);
            Oid oid = NUM2UINT(in_oid);

            if(lo_unlink(conn,oid) < 0)
                    rb_raise(rb_ePGerror,"lo_unlink failed");

            return Qnil;
    }

Also aliased as: lounlink
lo_write( lo_desc, buffer ) → Integer click to toggle source

Writes the string buffer to the large object lo_desc. Returns the number of bytes written.

    static VALUE
    pgconn_lowrite(VALUE self, VALUE in_lo_desc, VALUE buffer)
    {
            int n;
            PGconn *conn = pg_get_pgconn(self);
            int fd = NUM2INT(in_lo_desc);

            Check_Type(buffer, T_STRING);

            if( RSTRING_LEN(buffer) < 0) {
                    rb_raise(rb_ePGerror, "write buffer zero string");
            }
            if((n = lo_write(conn, fd, StringValuePtr(buffer),
                                    RSTRING_LEN(buffer))) < 0) {
                    rb_raise(rb_ePGerror, "lo_write failed: %s", PQerrorMessage(conn));
            }

            return INT2FIX(n);
    }

Also aliased as: lowrite
loclose(p1)
Alias for: lo_close
locreat(p1 = v1)
Alias for: lo_creat
locreate(p1)
Alias for: lo_create
loexport(p1, p2)
Alias for: lo_export
loimport(p1)
Alias for: lo_import
lolseek(p1, p2, p3)
Alias for: lo_lseek
loopen(p1, p2 = v2)
Alias for: lo_open
loread(p1, p2)
Alias for: lo_read
loseek(p1, p2, p3)
Alias for: lo_lseek
lotell(p1)
Alias for: lo_tell
lotruncate(p1, p2)
Alias for: lo_truncate
lounlink(p1)
Alias for: lo_unlink
lowrite(p1, p2)
Alias for: lo_write
make_empty_pgresult( status ) → PG::Result click to toggle source

Constructs and empty PG::Result with status status. status may be one of:

- `PGRES_EMPTY_QUERY`

- `PGRES_COMMAND_OK`

- `PGRES_TUPLES_OK`

- `PGRES_COPY_OUT`

- `PGRES_COPY_IN`

- `PGRES_BAD_RESPONSE`

- `PGRES_NONFATAL_ERROR`

- `PGRES_FATAL_ERROR`

- `PGRES_COPY_BOTH`

    static VALUE
    pgconn_make_empty_pgresult(VALUE self, VALUE status)
    {
            PGresult *result;
            VALUE rb_pgresult;
            PGconn *conn = pg_get_pgconn(self);
            result = PQmakeEmptyPGresult(conn, NUM2INT(status));
            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);
            return rb_pgresult;
    }

nonblocking?()
Alias for: isnonblocking
notifies() click to toggle source

Returns a hash of the unprocessed notifications. If there is no unprocessed notifier, it returns `nil`.

    static VALUE
    pgconn_notifies(VALUE self)
    {
            PGconn* conn = pg_get_pgconn(self);
            PGnotify *notification;
            VALUE hash;
            VALUE sym_relname, sym_be_pid, sym_extra;
            VALUE relname, be_pid, extra;

            sym_relname = ID2SYM(rb_intern("relname"));
            sym_be_pid = ID2SYM(rb_intern("be_pid"));
            sym_extra = ID2SYM(rb_intern("extra"));

            notification = gvl_PQnotifies(conn);
            if (notification == NULL) {
                    return Qnil;
            }

            hash = rb_hash_new();
            relname = rb_tainted_str_new2(notification->relname);
            be_pid = INT2NUM(notification->be_pid);
            extra = rb_tainted_str_new2(notification->extra);
            PG_ENCODING_SET_NOCHECK( relname, ENCODING_GET(self) );
            PG_ENCODING_SET_NOCHECK( extra, ENCODING_GET(self) );

            rb_hash_aset(hash, sym_relname, relname);
            rb_hash_aset(hash, sym_be_pid, be_pid);
            rb_hash_aset(hash, sym_extra, extra);

            PQfreemem(notification);
            return hash;
    }

notifies_wait(p1 = v1)
Alias for: wait_for_notify
options() click to toggle source

Returns backend option string.

    static VALUE
    pgconn_options(VALUE self)
    {
            char *options = PQoptions(pg_get_pgconn(self));
            if (!options) return Qnil;
            return rb_tainted_str_new2(options);
    }

parameter_status( param_name ) → String click to toggle source

Returns the setting of parameter param_name, where param_name is one of

- `server_version`

- `server_encoding`

- `client_encoding`

- `is_superuser`

- `session_authorization`

- `DateStyle`

- `TimeZone`

- `integer_datetimes`

- `standard_conforming_strings`

Returns nil if the value of the parameter is not known.

    static VALUE
    pgconn_parameter_status(VALUE self, VALUE param_name)
    {
            const char *ret = PQparameterStatus(pg_get_pgconn(self), StringValueCStr(param_name));
            if(ret == NULL)
                    return Qnil;
            else
                    return rb_tainted_str_new2(ret);
    }

pass() click to toggle source

Returns the authenticated password.

    static VALUE
    pgconn_pass(VALUE self)
    {
            char *user = PQpass(pg_get_pgconn(self));
            if (!user) return Qnil;
            return rb_tainted_str_new2(user);
    }

port() click to toggle source

Returns the connected server port number.

    static VALUE
    pgconn_port(VALUE self)
    {
            char* port = PQport(pg_get_pgconn(self));
            return INT2NUM(atol(port));
    }

protocol_version → Integer click to toggle source

The 3.0 protocol will normally be used when communicating with PostgreSQL 7.4 or later servers; pre-7.4 servers support only protocol 2.0. (Protocol 1.0 is obsolete and not supported by libpq.)

    static VALUE
    pgconn_protocol_version(VALUE self)
    {
            return INT2NUM(PQprotocolVersion(pg_get_pgconn(self)));
    }

put_copy_data( buffer [, encoder] ) → Boolean click to toggle source

Transmits buffer as copy data to the server. Returns true if the data was sent, false if it was not sent (false is only possible if the connection is in nonblocking mode, and this command would block).

encoder can be a PG::Coder derivation (typically PG::TextEncoder::CopyRow). This encodes the data fields given as buffer from an Array of Strings to PostgreSQL's COPY text format inclusive proper escaping. Optionally the encoder can type cast the fields from various Ruby types in one step, if PG::CopyCoder#type_map is set accordingly.

Raises an exception if an error occurs.

See also copy_data.

    static VALUE
    pgconn_put_copy_data(int argc, VALUE *argv, VALUE self)
    {
            int ret;
            int len;
            t_pg_connection *this = pg_get_connection_safe( self );
            VALUE value;
            VALUE buffer = Qnil;
            VALUE encoder;
            VALUE intermediate;
            t_pg_coder *p_coder = NULL;

            rb_scan_args( argc, argv, "11", &value, &encoder );

            if( NIL_P(encoder) ){
                    if( NIL_P(this->encoder_for_put_copy_data) ){
                            buffer = value;
                    } else {
                            p_coder = DATA_PTR( this->encoder_for_put_copy_data );
                    }
            } else if( rb_obj_is_kind_of(encoder, rb_cPG_Coder) ) {
                    Data_Get_Struct( encoder, t_pg_coder, p_coder );
            } else {
                    rb_raise( rb_eTypeError, "wrong encoder type %s (expected some kind of PG::Coder)",
                                    rb_obj_classname( encoder ) );
            }

            if( p_coder ){
                    t_pg_coder_enc_func enc_func;
                    int enc_idx = ENCODING_GET(self);

                    enc_func = pg_coder_enc_func( p_coder );
                    len = enc_func( p_coder, value, NULL, &intermediate, enc_idx);

                    if( len == -1 ){
                            /* The intermediate value is a String that can be used directly. */
                            buffer = intermediate;
                    } else {
                            buffer = rb_str_new(NULL, len);
                            len = enc_func( p_coder, value, RSTRING_PTR(buffer), &intermediate, enc_idx);
                            rb_str_set_len( buffer, len );
                    }
            }

            Check_Type(buffer, T_STRING);

            ret = gvl_PQputCopyData(this->pgconn, RSTRING_PTR(buffer), RSTRING_LENINT(buffer));
            if(ret == -1) {
                    VALUE error = rb_exc_new2(rb_ePGerror, PQerrorMessage(this->pgconn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            RB_GC_GUARD(intermediate);
            RB_GC_GUARD(buffer);

            return (ret) ? Qtrue : Qfalse;
    }

put_copy_end( [ error_message ] ) → Boolean click to toggle source

Sends end-of-data indication to the server.

error_message is an optional parameter, and if set, forces the COPY command to fail with the string error_message.

Returns true if the end-of-data was sent, false if it was not sent (false is only possible if the connection is in nonblocking mode, and this command would block).

    static VALUE
    pgconn_put_copy_end(int argc, VALUE *argv, VALUE self)
    {
            VALUE str;
            VALUE error;
            int ret;
            const char *error_message = NULL;
            PGconn *conn = pg_get_pgconn(self);

            if (rb_scan_args(argc, argv, "01", &str) == 0)
                    error_message = NULL;
            else
                    error_message = pg_cstr_enc(str, ENCODING_GET(self));

            ret = gvl_PQputCopyEnd(conn, error_message);
            if(ret == -1) {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return (ret) ? Qtrue : Qfalse;
    }

quote_ident( str ) → String click to toggle source
quote_ident( array ) → String
PG::Connection.quote_ident( str ) → String
PG::Connection.quote_ident( array ) → String

Returns a string that is safe for inclusion in a SQL query as an identifier. Note: this is not a quote function for values, but for identifiers.

For example, in a typical SQL query: `SELECT FOO FROM MYTABLE` The identifier `FOO` is folded to lower case, so it actually means `foo`. If you really want to access the case-sensitive field name `FOO`, use this function like `conn.quote_ident('FOO')`, which will return `"FOO"` (with double-quotes). PostgreSQL will see the double-quotes, and it will not fold to lower case.

Similarly, this function also protects against special characters, and other things that might allow SQL injection if the identifier comes from an untrusted source.

If the parameter is an Array, then all it's values are separately quoted and then joined by a “.” character. This can be used for identifiers in the form “schema”.“table”.“column” .

This method is functional identical to the encoder PG::TextEncoder::Identifier .

If the instance method form is used and the input string character encoding is different to the connection encoding, then the string is converted to this encoding, so that the returned string is always encoded as #internal_encoding .

In the singleton form (PG::Connection.quote_ident) the character encoding of the result string is set to the character encoding of the input string.

    static VALUE
    pgconn_s_quote_ident(VALUE self, VALUE str_or_array)
    {
            VALUE ret;
            int enc_idx;

            if( rb_obj_is_kind_of(self, rb_cPGconn) ){
                    enc_idx = ENCODING_GET( self );
            }else{
                    enc_idx = RB_TYPE_P(str_or_array, T_STRING) ? ENCODING_GET( str_or_array ) : rb_ascii8bit_encindex();
            }
            pg_text_enc_identifier(NULL, str_or_array, NULL, &ret, enc_idx);

            OBJ_INFECT(ret, str_or_array);

            return ret;
    }

reset() click to toggle source

Resets the backend connection. This method closes the backend connection and tries to re-connect.

    static VALUE
    pgconn_reset( VALUE self )
    {
            pgconn_close_socket_io( self );
            gvl_PQreset( pg_get_pgconn(self) );
            return self;
    }

reset_poll → Integer click to toggle source

Checks the status of a connection reset operation. See connect_start and connect_poll for usage information and return values.

    static VALUE
    pgconn_reset_poll(VALUE self)
    {
            PostgresPollingStatusType status;
            status = gvl_PQresetPoll(pg_get_pgconn(self));
            return INT2FIX((int)status);
    }

reset_start() → nil click to toggle source

Initiate a connection reset in a nonblocking manner. This will close the current connection and attempt to reconnect using the same connection parameters. Use reset_poll to check the status of the connection reset.

    static VALUE
    pgconn_reset_start(VALUE self)
    {
            pgconn_close_socket_io( self );
            if(gvl_PQresetStart(pg_get_pgconn(self)) == 0)
                    rb_raise(rb_eUnableToSend, "reset has failed");
            return Qnil;
    }

send_describe_portal( portal_name ) → nil click to toggle source

Asynchronously send command to the server. Does not block. Use in combination with `conn.get_result`.

    static VALUE
    pgconn_send_describe_portal(VALUE self, VALUE portal)
    {
            VALUE error;
            PGconn *conn = pg_get_pgconn(self);
            /* returns 0 on failure */
            if(gvl_PQsendDescribePortal(conn, pg_cstr_enc(portal, ENCODING_GET(self))) == 0) {
                    error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

send_describe_prepared( statement_name ) → nil click to toggle source

Asynchronously send command to the server. Does not block. Use in combination with `conn.get_result`.

    static VALUE
    pgconn_send_describe_prepared(VALUE self, VALUE stmt_name)
    {
            VALUE error;
            PGconn *conn = pg_get_pgconn(self);
            /* returns 0 on failure */
            if(gvl_PQsendDescribePrepared(conn, pg_cstr_enc(stmt_name, ENCODING_GET(self))) == 0) {
                    error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

send_prepare( stmt_name, sql [, param_types ] ) → nil click to toggle source

Prepares statement sql with name name to be executed later. Sends prepare command asynchronously, and returns immediately. On failure, it raises a PG::Error.

`param_types` is an optional parameter to specify the Oids of the types of the parameters.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it's recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query.

    static VALUE
    pgconn_send_prepare(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            int result;
            VALUE name, command, in_paramtypes;
            VALUE param;
            VALUE error;
            int i = 0;
            int nParams = 0;
            Oid *paramTypes = NULL;
            const char *name_cstr;
            const char *command_cstr;
            int enc_idx = ENCODING_GET(self);

            rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
            name_cstr = pg_cstr_enc(name, enc_idx);
            command_cstr = pg_cstr_enc(command, enc_idx);

            if(! NIL_P(in_paramtypes)) {
                    Check_Type(in_paramtypes, T_ARRAY);
                    nParams = (int)RARRAY_LEN(in_paramtypes);
                    paramTypes = ALLOC_N(Oid, nParams);
                    for(i = 0; i < nParams; i++) {
                            param = rb_ary_entry(in_paramtypes, i);
                            if(param == Qnil)
                                    paramTypes[i] = 0;
                            else
                                    paramTypes[i] = NUM2UINT(param);
                    }
            }
            result = gvl_PQsendPrepare(conn, name_cstr, command_cstr, nParams, paramTypes);

            xfree(paramTypes);

            if(result == 0) {
                    error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

send_query(sql) → nil click to toggle source

Sends SQL query request specified by sql to PostgreSQL for asynchronous processing, and immediately returns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call send_query_params for you. New code should explicitly use send_query_params if argument placeholders are used.

    static VALUE
    pgconn_send_query(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            VALUE error;

            /* If called with no or nil parameters, use PQexec for compatibility */
            if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                    if(gvl_PQsendQuery(conn, pg_cstr_enc(argv[0], ENCODING_GET(self))) == 0) {
                            error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                            rb_iv_set(error, "@connection", self);
                            rb_exc_raise(error);
                    }
                    return Qnil;
            }

            pg_deprecated(2, ("forwarding async_exec to async_exec_params and send_query to send_query_params is deprecated"));

            /* If called with parameters, and optionally result_format,
             * use PQsendQueryParams
             */
            return pgconn_send_query_params( argc, argv, self);
    }

send_query_params(sql, params [, result_format [, type_map ]] ) → nil click to toggle source

Sends SQL query request specified by sql to PostgreSQL for asynchronous processing, and immediately returns. On failure, it raises a PG::Error.

`params` is an array of the bind parameters for the SQL query. Each element of the `params` array may be either:

    a hash of the form:
      {:value  => String (value of bind parameter)
       :type   => Integer (oid of type of bind parameter)
       :format => Integer (0 for text, 1 for binary)
      }
    or, it may be a String. If it is a string, that is equivalent to the hash:
      { :value => <string value>, :type => 0, :format => 0 }

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query. The 0th element of the `params` array is bound to $1, the 1st element is bound to $2, etc. `nil` is treated as `NULL`.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it's recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

The optional `result_format` should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

    static VALUE
    pgconn_send_query_params(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            int result;
            VALUE command, in_res_fmt;
            VALUE error;
            int nParams;
            int resultFormat;
            struct query_params_data paramsData = { ENCODING_GET(self) };

            rb_scan_args(argc, argv, "22", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
            paramsData.with_types = 1;

            pgconn_query_assign_typemap( self, &paramsData );
            resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
            nParams = alloc_query_params( &paramsData );

            result = gvl_PQsendQueryParams(conn, pg_cstr_enc(command, paramsData.enc_idx), nParams, paramsData.types,
                    (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats, resultFormat);

            free_query_params( &paramsData );

            if(result == 0) {
                    error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

send_query_prepared( statement_name [, params, result_format[, type_map ]] ) click to toggle source
→ nil

Execute prepared named statement specified by statement_name asynchronously, and returns immediately. On failure, it raises a PG::Error.

`params` is an array of the optional bind parameters for the SQL query. Each element of the `params` array may be either:

    a hash of the form:
      {:value  => String (value of bind parameter)
       :format => Integer (0 for text, 1 for binary)
      }
    or, it may be a String. If it is a string, that is equivalent to the hash:
      { :value => <string value>, :format => 0 }

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query. The 0th element of the `params` array is bound to $1, the 1st element is bound to $2, etc. `nil` is treated as `NULL`.

The optional `result_format` should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

    static VALUE
    pgconn_send_query_prepared(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            int result;
            VALUE name, in_res_fmt;
            VALUE error;
            int nParams;
            int resultFormat;
            struct query_params_data paramsData = { ENCODING_GET(self) };

            rb_scan_args(argc, argv, "13", &name, &paramsData.params, &in_res_fmt, &paramsData.typemap);
            paramsData.with_types = 0;

            if(NIL_P(paramsData.params)) {
                    paramsData.params = rb_ary_new2(0);
                    resultFormat = 0;
            }
            pgconn_query_assign_typemap( self, &paramsData );

            resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
            nParams = alloc_query_params( &paramsData );

            result = gvl_PQsendQueryPrepared(conn, pg_cstr_enc(name, paramsData.enc_idx), nParams,
                    (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats,
                    resultFormat);

            free_query_params( &paramsData );

            if(result == 0) {
                    error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

server_version → Integer click to toggle source

The number is formed by converting the major, minor, and revision numbers into two-decimal-digit numbers and appending them together. For example, version 7.4.2 will be returned as 70402, and version 8.1 will be returned as 80100 (leading zeroes are not shown). Zero is returned if the connection is bad.

    static VALUE
    pgconn_server_version(VALUE self)
    {
            return INT2NUM(PQserverVersion(pg_get_pgconn(self)));
    }

set_client_encoding( encoding ) click to toggle source

Sets the client encoding to the encoding String.

    static VALUE
    pgconn_set_client_encoding(VALUE self, VALUE str)
    {
            PGconn *conn = pg_get_pgconn( self );

            Check_Type(str, T_STRING);

            if ( (gvl_PQsetClientEncoding(conn, StringValueCStr(str))) == -1 ) {
                    rb_raise(rb_ePGerror, "%s", PQerrorMessage(conn));
            }
            pgconn_set_internal_encoding_index( self );

            return Qnil;
    }

Also aliased as: client_encoding=
set_default_encoding() → Encoding click to toggle source

If Ruby has its Encoding.default_internal set, set PostgreSQL's client_encoding to match. Returns the new Encoding, or `nil` if the default internal encoding wasn't set.

    static VALUE
    pgconn_set_default_encoding( VALUE self )
    {
            PGconn *conn = pg_get_pgconn( self );
            rb_encoding *enc;
            const char *encname;

            if (( enc = rb_default_internal_encoding() )) {
                    encname = pg_get_rb_encoding_as_pg_encoding( enc );
                    if ( pgconn_set_client_encoding_async(self, encname) != 0 )
                            rb_warning( "Failed to set the default_internal encoding to %s: '%s'",
                                     encname, PQerrorMessage(conn) );
                    pgconn_set_internal_encoding_index( self );
                    return rb_enc_from_encoding( enc );
            } else {
                    pgconn_set_internal_encoding_index( self );
                    return Qnil;
            }
    }

set_error_verbosity( verbosity ) → Integer click to toggle source

Sets connection's verbosity to verbosity and returns the previous setting. Available settings are:

- PQERRORS_TERSE

- PQERRORS_DEFAULT

- PQERRORS_VERBOSE

    static VALUE
    pgconn_set_error_verbosity(VALUE self, VALUE in_verbosity)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGVerbosity verbosity = NUM2INT(in_verbosity);
            return INT2FIX(PQsetErrorVerbosity(conn, verbosity));
    }

set_notice_processor {|message| ... } → Proc click to toggle source

See set_notice_receiver for the desription of what this and the notice_processor methods do.

This function takes a new block to act as the notice processor and returns the Proc object previously set, or `nil` if it was previously the default. The block should accept a single String object.

If you pass no arguments, it will reset the handler to the default.

    static VALUE
    pgconn_set_notice_processor(VALUE self)
    {
            VALUE proc, old_proc;
            t_pg_connection *this = pg_get_connection_safe( self );

            /* If default_notice_processor is unset, assume that the current
             * notice processor is the default, and save it to a global variable.
             * This should not be a problem because the default processor is
             * always the same, so won't vary among connections.
             */
            if(default_notice_processor == NULL)
                    default_notice_processor = PQsetNoticeProcessor(this->pgconn, NULL, NULL);

            old_proc = this->notice_receiver;
            if( rb_block_given_p() ) {
                    proc = rb_block_proc();
                    PQsetNoticeProcessor(this->pgconn, gvl_notice_processor_proxy, (void *)self);
            } else {
                    /* if no block is given, set back to default */
                    proc = Qnil;
                    PQsetNoticeProcessor(this->pgconn, default_notice_processor, NULL);
            }

            this->notice_receiver = proc;
            return old_proc;
    }

set_notice_receiver {|result| ... } → Proc click to toggle source

Notice and warning messages generated by the server are not returned by the query execution functions, since they do not imply failure of the query. Instead they are passed to a notice handling function, and execution continues normally after the handler returns. The default notice handling function prints the message on `stderr`, but the application can override this behavior by supplying its own handling function.

For historical reasons, there are two levels of notice handling, called the notice receiver and notice processor. The default behavior is for the notice receiver to format the notice and pass a string to the notice processor for printing. However, an application that chooses to provide its own notice receiver will typically ignore the notice processor layer and just do all the work in the notice receiver.

This function takes a new block to act as the handler, which should accept a single parameter that will be a PG::Result object, and returns the Proc object previously set, or `nil` if it was previously the default.

If you pass no arguments, it will reset the handler to the default.

Note: The `result` passed to the block should not be used outside of the block, since the corresponding C object could be freed after the block finishes.

    static VALUE
    pgconn_set_notice_receiver(VALUE self)
    {
            VALUE proc, old_proc;
            t_pg_connection *this = pg_get_connection_safe( self );

            /* If default_notice_receiver is unset, assume that the current
             * notice receiver is the default, and save it to a global variable.
             * This should not be a problem because the default receiver is
             * always the same, so won't vary among connections.
             */
            if(default_notice_receiver == NULL)
                    default_notice_receiver = PQsetNoticeReceiver(this->pgconn, NULL, NULL);

            old_proc = this->notice_receiver;
            if( rb_block_given_p() ) {
                    proc = rb_block_proc();
                    PQsetNoticeReceiver(this->pgconn, gvl_notice_receiver_proxy, (void *)self);
            } else {
                    /* if no block is given, set back to default */
                    proc = Qnil;
                    PQsetNoticeReceiver(this->pgconn, default_notice_receiver, NULL);
            }

            this->notice_receiver = proc;
            return old_proc;
    }

set_single_row_mode → self click to toggle source

To enter single-row mode, call this method immediately after a successful call of #send_query (or a sibling function). This mode selection is effective only for the currently executing query. Then call #get_result repeatedly, until it returns nil.

Each (but the last) received Result has exactly one row and a Result#result_status of PGRES_SINGLE_TUPLE. The last Result has zero rows and is used to indicate a successful execution of the query. All of these Result objects will contain the same row description data (column names, types, etc) that an ordinary Result object for the query would have.

Caution: While processing a query, the server may return some rows and then encounter an error, causing the query to be aborted. Ordinarily, pg discards any such rows and reports only the error. But in single-row mode, those rows will have already been returned to the application. Hence, the application will see some Result objects followed by an Error raised in get_result. For proper transactional behavior, the application must be designed to discard or undo whatever has been done with the previously-processed rows, if the query ultimately fails.

Example:

    conn.send_query( "your SQL command" )
    conn.set_single_row_mode
    loop do
      res = conn.get_result or break
      res.check
      res.each do |row|
        # do something with the received row
      end
    end

Available since PostgreSQL-9.2

    static VALUE
    pgconn_set_single_row_mode(VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            VALUE error;

            if( PQsetSingleRowMode(conn) == 0 )
            {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }

            return self;
    }

setnonblocking(Boolean) → nil click to toggle source

Sets the nonblocking status of the connection. In the blocking state, calls to send_query will block until the message is sent to the server, but will not wait for the query results. In the nonblocking state, calls to send_query will return an error if the socket is not ready for writing. Note: This function does not affect exec, because that function doesn't return until the server has processed the query and returned the results. Returns `nil`.

    static VALUE
    pgconn_setnonblocking(self, state)
            VALUE self, state;
    {
            int arg;
            VALUE error;
            PGconn *conn = pg_get_pgconn(self);
            if(state == Qtrue)
                    arg = 1;
            else if (state == Qfalse)
                    arg = 0;
            else
                    rb_raise(rb_eArgError, "Boolean value expected");

            if(PQsetnonblocking(conn, arg) == -1) {
                    error = rb_exc_new2(rb_ePGerror, PQerrorMessage(conn));
                    rb_iv_set(error, "@connection", self);
                    rb_exc_raise(error);
            }
            return Qnil;
    }

socket() → Integer click to toggle source

This method is deprecated. Please use the more portable method socket_io .

Returns the socket's file descriptor for this connection. `IO.for_fd()` can be used to build a proper IO object to the socket. If you do so, you will likely also want to set `autoclose=false` on it to prevent Ruby from closing the socket to PostgreSQL if it goes out of scope. Alternatively, you can use socket_io, which creates an IO that's associated with the connection object itself, and so won't go out of scope until the connection does.

Note: On Windows the file descriptor is not usable, since it can not be used to build a Ruby IO object.

    static VALUE
    pgconn_socket(VALUE self)
    {
            int sd;
            if( (sd = PQsocket(pg_get_pgconn(self))) < 0)
                    rb_raise(rb_eConnectionBad, "PQsocket() can't get socket descriptor");
            return INT2NUM(sd);
    }

socket_io() → IO click to toggle source

Fetch a memorized IO object created from the Connection's underlying socket. This object can be used for IO.select to wait for events while running asynchronous API calls.

Using this instead of socket avoids the problem of the underlying connection being closed by Ruby when an IO created using `IO.for_fd(conn.socket)` goes out of scope. In contrast to socket, it also works on Windows.

    static VALUE
    pgconn_socket_io(VALUE self)
    {
            int sd;
            int ruby_sd;
            ID id_autoclose = rb_intern("autoclose=");
            t_pg_connection *this = pg_get_connection_safe( self );
            VALUE socket_io = this->socket_io;

            if ( !RTEST(socket_io) ) {
                    if( (sd = PQsocket(this->pgconn)) < 0)
                            rb_raise(rb_eConnectionBad, "PQsocket() can't get socket descriptor");

                    #ifdef _WIN32
                            ruby_sd = rb_w32_wrap_io_handle((HANDLE)(intptr_t)sd, O_RDWR|O_BINARY|O_NOINHERIT);
                            this->ruby_sd = ruby_sd;
                    #else
                            ruby_sd = sd;
                    #endif

                    socket_io = rb_funcall( rb_cIO, rb_intern("for_fd"), 1, INT2NUM(ruby_sd) );

                    /* Disable autoclose feature */
                    rb_funcall( socket_io, id_autoclose, 1, Qfalse );

                    this->socket_io = socket_io;
            }

            return socket_io;
    }

ssl_attribute(attribute_name) → String click to toggle source

Returns SSL-related information about the connection.

The list of available attributes varies depending on the SSL library being used, and the type of connection. If an attribute is not available, returns nil.

The following attributes are commonly available:

`library`

  Name of the SSL implementation in use. (Currently, only “OpenSSL” is implemented)

`protocol`

  SSL/TLS version in use. Common values are “SSLv2”, “SSLv3”, “TLSv1”, “TLSv1.1” and “TLSv1.2”, but an implementation may return other strings if some other protocol is used.

`key_bits`

  Number of key bits used by the encryption algorithm.

`cipher`

  A short name of the ciphersuite used, e.g. “DHE-RSA-DES-CBC3-SHA”. The names are specific to each SSL implementation.

`compression`

  If SSL compression is in use, returns the name of the compression algorithm, or “on” if compression is used but the algorithm is not known. If compression is not in use, returns “off”.

See also ssl_attribute_names and www.postgresql.org/docs/current/interactive/libpq-status.html#LIBPQ-PQSSLATTRIBUTE

Available since PostgreSQL-9.5

    static VALUE
    pgconn_ssl_attribute(VALUE self, VALUE attribute_name)
    {
            const char *p_attr;

            p_attr = PQsslAttribute(pg_get_pgconn(self), StringValueCStr(attribute_name));
            return p_attr ? rb_str_new_cstr(p_attr) : Qnil;
    }

ssl_attribute_names → Array<String> click to toggle source

Return an array of SSL attribute names available.

See also ssl_attribute

Available since PostgreSQL-9.5

    static VALUE
    pgconn_ssl_attribute_names(VALUE self)
    {
            int i;
            const char * const * p_list = PQsslAttributeNames(pg_get_pgconn(self));
            VALUE ary = rb_ary_new();

            for ( i = 0; p_list[i]; i++ ) {
                    rb_ary_push( ary, rb_str_new_cstr( p_list[i] ));
            }
            return ary;
    }

ssl_attributes → Hash<String,String> click to toggle source

Returns SSL-related information about the connection as key/value pairs

The available attributes varies depending on the SSL library being used, and the type of connection.

See also ssl_attribute

    # File lib/pg/connection.rb, line 263
    def ssl_attributes
            ssl_attribute_names.each.with_object({}) do |n,h|
                    h[n] = ssl_attribute(n)
            end
    end

ssl_in_use? → Boolean click to toggle source

Returns `true` if the connection uses SSL, `false` if not.

Available since PostgreSQL-9.5

    static VALUE
    pgconn_ssl_in_use(VALUE self)
    {
            return PQsslInUse(pg_get_pgconn(self)) ? Qtrue : Qfalse;
    }

status() click to toggle source

Returns status of connection : CONNECTION_OK or CONNECTION_BAD

    static VALUE
    pgconn_status(VALUE self)
    {
            return INT2NUM(PQstatus(pg_get_pgconn(self)));
    }

describe_portal( portal_name ) → PG::Result click to toggle source

Retrieve information about the portal portal_name.

    static VALUE
    pgconn_describe_portal(self, stmt_name)
            VALUE self, stmt_name;
    {
            PGresult *result;
            VALUE rb_pgresult;
            PGconn *conn = pg_get_pgconn(self);
            const char *stmt;
            if(NIL_P(stmt_name)) {
                    stmt = NULL;
            }
            else {
                    stmt = pg_cstr_enc(stmt_name, ENCODING_GET(self));
            }
            result = gvl_PQdescribePortal(conn, stmt);
            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);
            return rb_pgresult;
    }

describe_prepared( statement_name ) → PG::Result click to toggle source

Retrieve information about the prepared statement statement_name.

    static VALUE
    pgconn_describe_prepared(VALUE self, VALUE stmt_name)
    {
            PGresult *result;
            VALUE rb_pgresult;
            PGconn *conn = pg_get_pgconn(self);
            const char *stmt;
            if(NIL_P(stmt_name)) {
                    stmt = NULL;
            }
            else {
                    stmt = pg_cstr_enc(stmt_name, ENCODING_GET(self));
            }
            result = gvl_PQdescribePrepared(conn, stmt);
            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);
            return rb_pgresult;
    }

exec(sql) → PG::Result click to toggle source
exec(sql) {|pg_result| block }

Sends SQL query request specified by sql to PostgreSQL. On success, it returns a PG::Result instance with all result rows and columns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call exec_params for you. New code should explicitly use exec_params if argument placeholders are used.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, `conn.exec` returns the value of the block.

sync_exec is implemented on the synchronous command processing API of libpq, whereas async_exec is implemented on the asynchronous API. sync_exec is somewhat faster that async_exec, but blocks any signals to be processed until the query is finished. This is most notably visible by a delayed reaction to Control+C. Both methods ensure that other threads can process while waiting for the server to complete the request.

    static VALUE
    pgconn_exec(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result = NULL;
            VALUE rb_pgresult;

            /* If called with no or nil parameters, use PQexec for compatibility */
            if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                    VALUE query_str = argv[0];

                    result = gvl_PQexec(conn, pg_cstr_enc(query_str, ENCODING_GET(self)));
                    rb_pgresult = pg_new_result(result, self);
                    pg_result_check(rb_pgresult);
                    if (rb_block_given_p()) {
                            return rb_ensure(rb_yield, rb_pgresult, pg_result_clear, rb_pgresult);
                    }
                    return rb_pgresult;
            }
            pg_deprecated(0, ("forwarding exec to exec_params is deprecated"));

            /* Otherwise, just call #exec_params instead for backward-compatibility */
            return pgconn_exec_params( argc, argv, self );

    }

exec_params(sql, params[, result_format[, type_map]] ) → PG::Result click to toggle source
exec_params(sql, params[, result_format[, type_map]] ) {|pg_result| block }

Sends SQL query request specified by `sql` to PostgreSQL using placeholders for parameters.

Returns a PG::Result instance on success. On failure, it raises a PG::Error.

`params` is an array of the bind parameters for the SQL query. Each element of the `params` array may be either:

    a hash of the form:
      {:value  => String (value of bind parameter)
       :type   => Integer (oid of type of bind parameter)
       :format => Integer (0 for text, 1 for binary)
      }
    or, it may be a String. If it is a string, that is equivalent to the hash:
      { :value => <string value>, :type => 0, :format => 0 }

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query. The 0th element of the `params` array is bound to $1, the 1st element is bound to $2, etc. `nil` is treated as `NULL`.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it's recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

The optional `result_format` should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, `conn.exec` returns the value of the block.

    static VALUE
    pgconn_exec_params( int argc, VALUE *argv, VALUE self )
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result = NULL;
            VALUE rb_pgresult;
            VALUE command, in_res_fmt;
            int nParams;
            int resultFormat;
            struct query_params_data paramsData = { ENCODING_GET(self) };

            /* For compatibility we accept 1 to 4 parameters */
            rb_scan_args(argc, argv, "13", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
            paramsData.with_types = 1;

            /*
             * For backward compatibility no or +nil+ for the second parameter
             * is passed to #exec
             */
            if ( NIL_P(paramsData.params) ) {
                    pg_deprecated(1, ("forwarding exec_params to exec is deprecated"));
                    return pgconn_exec( 1, argv, self );
            }
            pgconn_query_assign_typemap( self, &paramsData );

            resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
            nParams = alloc_query_params( &paramsData );

            result = gvl_PQexecParams(conn, pg_cstr_enc(command, paramsData.enc_idx), nParams, paramsData.types,
                    (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats, resultFormat);

            free_query_params( &paramsData );

            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);

            if (rb_block_given_p()) {
                    return rb_ensure(rb_yield, rb_pgresult, pg_result_clear, rb_pgresult);
            }

            return rb_pgresult;
    }

exec_prepared(statement_name [, params, result_format[, type_map]] ) → PG::Result click to toggle source
exec_prepared(statement_name [, params, result_format[, type_map]] ) {|pg_result| block }

Execute prepared named statement specified by statement_name. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

`params` is an array of the optional bind parameters for the SQL query. Each element of the `params` array may be either:

    a hash of the form:
      {:value  => String (value of bind parameter)
       :format => Integer (0 for text, 1 for binary)
      }
    or, it may be a String. If it is a string, that is equivalent to the hash:
      { :value => <string value>, :format => 0 }

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query. The 0th element of the `params` array is bound to $1, the 1st element is bound to $2, etc. `nil` is treated as `NULL`.

The optional `result_format` should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, `conn.exec_prepared` returns the value of the block.

    static VALUE
    pgconn_exec_prepared(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result = NULL;
            VALUE rb_pgresult;
            VALUE name, in_res_fmt;
            int nParams;
            int resultFormat;
            struct query_params_data paramsData = { ENCODING_GET(self) };

            rb_scan_args(argc, argv, "13", &name, &paramsData.params, &in_res_fmt, &paramsData.typemap);
            paramsData.with_types = 0;

            if(NIL_P(paramsData.params)) {
                    paramsData.params = rb_ary_new2(0);
            }
            pgconn_query_assign_typemap( self, &paramsData );

            resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
            nParams = alloc_query_params( &paramsData );

            result = gvl_PQexecPrepared(conn, pg_cstr_enc(name, paramsData.enc_idx), nParams,
                    (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats,
                    resultFormat);

            free_query_params( &paramsData );

            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);
            if (rb_block_given_p()) {
                    return rb_ensure(rb_yield, rb_pgresult,
                            pg_result_clear, rb_pgresult);
            }
            return rb_pgresult;
    }

prepare(stmt_name, sql [, param_types ] ) → PG::Result click to toggle source

Prepares statement sql with name name to be executed later. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

`param_types` is an optional parameter to specify the Oids of the types of the parameters.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it's recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

PostgreSQL bind parameters are represented as $1, $1, $2, etc., inside the SQL query.

    static VALUE
    pgconn_prepare(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result = NULL;
            VALUE rb_pgresult;
            VALUE name, command, in_paramtypes;
            VALUE param;
            int i = 0;
            int nParams = 0;
            Oid *paramTypes = NULL;
            const char *name_cstr;
            const char *command_cstr;
            int enc_idx = ENCODING_GET(self);

            rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
            name_cstr = pg_cstr_enc(name, enc_idx);
            command_cstr = pg_cstr_enc(command, enc_idx);

            if(! NIL_P(in_paramtypes)) {
                    Check_Type(in_paramtypes, T_ARRAY);
                    nParams = (int)RARRAY_LEN(in_paramtypes);
                    paramTypes = ALLOC_N(Oid, nParams);
                    for(i = 0; i < nParams; i++) {
                            param = rb_ary_entry(in_paramtypes, i);
                            if(param == Qnil)
                                    paramTypes[i] = 0;
                            else
                                    paramTypes[i] = NUM2UINT(param);
                    }
            }
            result = gvl_PQprepare(conn, name_cstr, command_cstr, nParams, paramTypes);

            xfree(paramTypes);

            rb_pgresult = pg_new_result(result, self);
            pg_result_check(rb_pgresult);
            return rb_pgresult;
    }

trace( stream ) → nil click to toggle source

Enables tracing message passing between backend. The trace message will be written to the stream stream, which must implement a method `fileno` that returns a writable file descriptor.

    static VALUE
    pgconn_trace(VALUE self, VALUE stream)
    {
            VALUE fileno;
            FILE *new_fp;
            int old_fd, new_fd;
            VALUE new_file;
            t_pg_connection *this = pg_get_connection_safe( self );

            if(rb_respond_to(stream,rb_intern("fileno")) == Qfalse)
                    rb_raise(rb_eArgError, "stream does not respond to method: fileno");

            fileno = rb_funcall(stream, rb_intern("fileno"), 0);
            if(fileno == Qnil)
                    rb_raise(rb_eArgError, "can't get file descriptor from stream");

            /* Duplicate the file descriptor and re-open
             * it. Then, make it into a ruby File object
             * and assign it to an instance variable.
             * This prevents a problem when the File
             * object passed to this function is closed
             * before the connection object is. */
            old_fd = NUM2INT(fileno);
            new_fd = dup(old_fd);
            new_fp = fdopen(new_fd, "w");

            if(new_fp == NULL)
                    rb_raise(rb_eArgError, "stream is not writable");

            new_file = rb_funcall(rb_cIO, rb_intern("new"), 1, INT2NUM(new_fd));
            this->trace_stream = new_file;

            PQtrace(this->pgconn, new_fp);
            return Qnil;
    }

transaction { |conn| ... } → result of the block click to toggle source

Executes a `BEGIN` at the start of the block, and a `COMMIT` at the end of the block, or `ROLLBACK` if any exception occurs.

    static VALUE
    pgconn_transaction(VALUE self)
    {
            PGconn *conn = pg_get_pgconn(self);
            PGresult *result;
            VALUE rb_pgresult;
            VALUE block_result = Qnil;
            int status;

            if (rb_block_given_p()) {
                    result = gvl_PQexec(conn, "BEGIN");
                    rb_pgresult = pg_new_result(result, self);
                    pg_result_check(rb_pgresult);
                    block_result = rb_protect(rb_yield, self, &status);
                    if(status == 0) {
                            result = gvl_PQexec(conn, "COMMIT");
                            rb_pgresult = pg_new_result(result, self);
                            pg_result_check(rb_pgresult);
                    }
                    else {
                            /* exception occurred, ROLLBACK and re-raise */
                            result = gvl_PQexec(conn, "ROLLBACK");
                            rb_pgresult = pg_new_result(result, self);
                            pg_result_check(rb_pgresult);
                            rb_jump_tag(status);
                    }

            }
            else {
                    /* no block supplied? */
                    rb_raise(rb_eArgError, "Must supply block for PG::Connection#transaction");
            }
            return block_result;
    }

transaction_status() click to toggle source

returns one of the following statuses:

    PQTRANS_IDLE    = 0 (connection idle)
    PQTRANS_ACTIVE  = 1 (command in progress)
    PQTRANS_INTRANS = 2 (idle, within transaction block)
    PQTRANS_INERROR = 3 (idle, within failed transaction)
    PQTRANS_UNKNOWN = 4 (cannot determine status)

    static VALUE
    pgconn_transaction_status(VALUE self)
    {
            return INT2NUM(PQtransactionStatus(pg_get_pgconn(self)));
    }

tty() click to toggle source

Returns the connected pgtty. (Obsolete)

    static VALUE
    pgconn_tty(VALUE self)
    {
            char *tty = PQtty(pg_get_pgconn(self));
            if (!tty) return Qnil;
            return rb_tainted_str_new2(tty);
    }

type_map_for_queries → TypeMap click to toggle source

Returns the default TypeMap that is currently set for type casts of query bind parameters.

    static VALUE
    pgconn_type_map_for_queries_get(VALUE self)
    {
            t_pg_connection *this = pg_get_connection( self );

            return this->type_map_for_queries;
    }

type_map_for_queries = typemap click to toggle source

Set the default TypeMap that is used for type casts of query bind parameters.

`typemap` must be a kind of PG::TypeMap .

    static VALUE
    pgconn_type_map_for_queries_set(VALUE self, VALUE typemap)
    {
            t_pg_connection *this = pg_get_connection( self );

            if ( !rb_obj_is_kind_of(typemap, rb_cTypeMap) ) {
                    rb_raise( rb_eTypeError, "wrong argument type %s (expected kind of PG::TypeMap)",
                                    rb_obj_classname( typemap ) );
            }
            Check_Type(typemap, T_DATA);
            this->type_map_for_queries = typemap;

            return typemap;
    }

type_map_for_results → TypeMap click to toggle source

Returns the default TypeMap that is currently set for type casts of result values.

    static VALUE
    pgconn_type_map_for_results_get(VALUE self)
    {
            t_pg_connection *this = pg_get_connection( self );

            return this->type_map_for_results;
    }

type_map_for_results = typemap click to toggle source

Set the default TypeMap that is used for type casts of result values.

`typemap` must be a kind of PG::TypeMap .

    static VALUE
    pgconn_type_map_for_results_set(VALUE self, VALUE typemap)
    {
            t_pg_connection *this = pg_get_connection( self );

            if ( !rb_obj_is_kind_of(typemap, rb_cTypeMap) ) {
                    rb_raise( rb_eTypeError, "wrong argument type %s (expected kind of PG::TypeMap)",
                                    rb_obj_classname( typemap ) );
            }
            Check_Type(typemap, T_DATA);
            this->type_map_for_results = typemap;

            return typemap;
    }

PG::Connection.unescape_bytea( string ) click to toggle source

Converts an escaped string representation of binary data into binary data — the reverse of escape_bytea. This is needed when retrieving `bytea` data in text format, but not when retrieving it in binary format.

    static VALUE
    pgconn_s_unescape_bytea(VALUE self, VALUE str)
    {
            unsigned char *from, *to;
            size_t to_len;
            VALUE ret;

            UNUSED( self );

            Check_Type(str, T_STRING);
            from = (unsigned char*)StringValueCStr(str);

            to = PQunescapeBytea(from, &to_len);

            ret = rb_str_new((char*)to, to_len);
            OBJ_INFECT(ret, str);
            PQfreemem(to);
            return ret;
    }

untrace() → nil click to toggle source

Disables the message tracing.

    static VALUE
    pgconn_untrace(VALUE self)
    {
            t_pg_connection *this = pg_get_connection_safe( self );

            PQuntrace(this->pgconn);
            rb_funcall(this->trace_stream, rb_intern("close"), 0);
            this->trace_stream = Qnil;
            return Qnil;
    }

user() click to toggle source

Returns the authenticated user name.

    static VALUE
    pgconn_user(VALUE self)
    {
            char *user = PQuser(pg_get_pgconn(self));
            if (!user) return Qnil;
            return rb_tainted_str_new2(user);
    }

wait_for_notify( [ timeout ] ) { |event, pid, payload| block } → String click to toggle source

Blocks while waiting for notification(s), or until the optional timeout is reached, whichever comes first. timeout is measured in seconds and can be fractional.

Returns `nil` if timeout is reached, the name of the NOTIFY event otherwise. If used in block form, passes the name of the NOTIFY `event`, the generating `pid` and the optional `payload` string into the block.

    static VALUE
    pgconn_wait_for_notify(int argc, VALUE *argv, VALUE self)
    {
            PGconn *conn = pg_get_pgconn( self );
            PGnotify *pnotification;
            struct timeval timeout;
            struct timeval *ptimeout = NULL;
            VALUE timeout_in = Qnil, relname = Qnil, be_pid = Qnil, extra = Qnil;
            double timeout_sec;

            rb_scan_args( argc, argv, "01", &timeout_in );

            if ( RTEST(timeout_in) ) {
                    timeout_sec = NUM2DBL( timeout_in );
                    timeout.tv_sec = (time_t)timeout_sec;
                    timeout.tv_usec = (suseconds_t)( (timeout_sec - (long)timeout_sec) * 1e6 );
                    ptimeout = &timeout;
            }

            pnotification = (PGnotify*) wait_socket_readable( conn, ptimeout, notify_readable);

            /* Return nil if the select timed out */
            if ( !pnotification ) return Qnil;

            relname = rb_tainted_str_new2( pnotification->relname );
            PG_ENCODING_SET_NOCHECK( relname, ENCODING_GET(self) );
            be_pid = INT2NUM( pnotification->be_pid );
            if ( *pnotification->extra ) {
                    extra = rb_tainted_str_new2( pnotification->extra );
                    PG_ENCODING_SET_NOCHECK( extra, ENCODING_GET(self) );
            }
            PQfreemem( pnotification );

            if ( rb_block_given_p() )
                    rb_yield_values( 3, relname, be_pid, extra );

            return relname;
    }

Also aliased as: notifies_wait