PG: The Ruby PostgreSQL Driver

Constants

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

Public Class Methods

anchor

PG::Connection.conndefaults() → Array

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;
}

anchor

conndefaults_hash()

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

Public Instance Methods

anchor

async_exec(sql [, params, result_format ] ) → PG::Result
async_exec(sql [, params, result_format ] ) {|pg_result| block }

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

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

        /* remove any remaining results from the queue */
        pgconn_block( 0, NULL, self ); /* wait for input (without blocking) before reading the last result */
        pgconn_get_last_result( self );

        pgconn_send_query( argc, argv, self );
        pgconn_block( 0, NULL, self );
        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

anchor

async_query(*args)

Alias for: async_exec

anchor

backend_pid() → Integer

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)));
}

anchor

block( [ timeout ] ) → Boolean

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 );

        /* If WIN32 and Ruby 1.9 do not use rb_thread_select() which sometimes hangs
         * and does not wait (nor sleep) any time even if timeout is given.
         * Instead use the Winsock events and rb_w32_wait_events(). */

        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;
}

anchor

cancel() → String

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;
}

anchor

client_encoding=(p1)

Alias for: set_client_encoding

anchor

close()

Alias for: finish

anchor

conndefaults()

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

anchor

conndefaults_hash()

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

anchor

connect_poll() → Integer

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);
}

anchor

connection_needs_password() → Boolean

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;
}

anchor

connection_used_password() → Boolean

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;
}

anchor

conninfo → hash

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;
}

anchor

conninfo_hash()

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

anchor

consume_input()

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;
}

anchor

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

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

anchor

db()

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);
}

anchor

decoder_for_get_copy_data → PG::Coder

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;
}

anchor

decoder_for_get_copy_data = decoder

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;
}

anchor

describe_portal( portal_name ) → PG::Result

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;
}

anchor

describe_prepared( statement_name ) → PG::Result

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;
}

anchor

encoder_for_put_copy_data → PG::Coder

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;
}

anchor

encoder_for_put_copy_data = encoder

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;
}

anchor

encrypt_password( password, username, algorithm=nil ) → String

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;
}

anchor

error_message → String

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);
}

anchor

escape(p1)

Alias for: escape_string

anchor

escape_bytea( string ) → String

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

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

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;
}

anchor

escape_identifier( str ) → String

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);

        Check_Type(string, T_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;
}

anchor

escape_literal( str ) → String

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);

        Check_Type(string, T_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;
}

anchor

escape_string( str ) → String

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.

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);

        Check_Type(string, T_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

anchor

exec(sql) → PG::Result
exec(sql) {|pg_result| block }

Sends SQL query request specified by sql to PostgreSQL. Returns a PG::Result instance on success. 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.

exec is implemented on the synchronous command processing API of libpq, whereas async_exec is implemented on the asynchronous API. 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 parameters, use PQexec */
        if ( argc == 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;
        }

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

}

Also aliased as: query

anchor

exec_params(sql, params[, result_format[, type_map]] ) → PG::Result
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.

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) };

        rb_scan_args(argc, argv, "13", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 1;

        /*
         * Handle the edge-case where the caller is coming from #exec, but passed an explict +nil+
         * for the second parameter.
         */
        if ( NIL_P(paramsData.params) ) {
                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;
}

anchor

exec_prepared(statement_name [, params, result_format[, type_map]] ) → PG::Result
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 }

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

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;
}

anchor

external_encoding() → Encoding

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;
}

anchor

finish

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

anchor

finished? → boolean

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;
}

anchor

flush() → Boolean

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;
}

anchor

get_client_encoding() → String

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);
}

anchor

get_copy_data( [ async = false [, decoder = nil ]] ) → String

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

decoder can be a PG::Coder derivation (typically PG::TextDecoder::CopyRow). This decodes the received data fields from PostgreSQL's COPY text format to an Array of Strings. Optionally the decoder can type cast the fields to various Ruby types in one step, if PG::CopyCoder#type_map is set accordingly.

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;
}

anchor

put_copy_end( [ error_message ] ) → Boolean

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;
}

anchor

query(*args)

Alias for: exec

anchor

quote_ident( str ) → String
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.

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 .

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;
}

anchor

reset()

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;
}

anchor

reset_poll → Integer

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);
}

anchor

reset_start() → nil

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;
}

anchor

send_describe_portal( portal_name ) → nil

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;
}

anchor

send_describe_prepared( statement_name ) → nil

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;
}

anchor

send_prepare( stmt_name, sql [, param_types ] ) → nil

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;
}

anchor

send_query(sql [, params, result_format[, type_map ]] ) → nil

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 optional 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 }

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.

static VALUE
pgconn_send_query(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, "13", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 1;

        /* If called with no parameters, use PQsendQuery */
        if(NIL_P(paramsData.params)) {
                if(gvl_PQsendQuery(conn, pg_cstr_enc(command, paramsData.enc_idx)) == 0) {
                        error = rb_exc_new2(rb_eUnableToSend, PQerrorMessage(conn));
                        rb_iv_set(error, "@connection", self);
                        rb_exc_raise(error);
                }
                return Qnil;
        }

        /* If called with parameters, and optionally result_format,
         * use PQsendQueryParams
         */

        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;
}

anchor

send_query_prepared( statement_name [, params, result_format[, type_map ]] )
→ 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 }

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

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;
}

anchor

server_version → Integer

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)));
}

anchor

set_client_encoding( encoding )

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=

anchor

set_default_encoding() → Encoding

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_warn( "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;
        }
}

anchor

set_error_verbosity( verbosity ) → Integer

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));
}

anchor

set_notice_processor {|message| ... } → Proc

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;
}

anchor

set_notice_receiver {|result| ... } → Proc

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;
}

anchor

set_single_row_mode → self

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;
}

anchor

setnonblocking(Boolean) → nil

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;
}

anchor

socket() → Integer

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);
}

anchor

socket_io() → IO

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);
                #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;
}

anchor

ssl_attribute(attribute_name) → String

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”.

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;
}

anchor

ssl_attribute_names → Array

Return an array of SSL attribute names available.