Class: PG::Connection

Inherits:
Object
  • Object
show all
Includes:
Constants
Defined in:
lib/pg/connection.rb,
ext/pg_connection.c

Overview

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.

Constant Summary

CONNECT_ARGUMENT_ORDER =

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

%w[host port options tty dbname user password]

Constants included from Constants

PG::Constants::CONNECTION_AUTH_OK, PG::Constants::CONNECTION_AWAITING_RESPONSE, PG::Constants::CONNECTION_BAD, PG::Constants::CONNECTION_MADE, PG::Constants::CONNECTION_NEEDED, PG::Constants::CONNECTION_OK, PG::Constants::CONNECTION_SETENV, PG::Constants::CONNECTION_SSL_STARTUP, PG::Constants::CONNECTION_STARTED, PG::Constants::INVALID_OID, PG::Constants::INV_READ, PG::Constants::INV_WRITE, PG::Constants::InvalidOid, PG::Constants::PGRES_BAD_RESPONSE, PG::Constants::PGRES_COMMAND_OK, PG::Constants::PGRES_COPY_BOTH, PG::Constants::PGRES_COPY_IN, PG::Constants::PGRES_COPY_OUT, PG::Constants::PGRES_EMPTY_QUERY, PG::Constants::PGRES_FATAL_ERROR, PG::Constants::PGRES_NONFATAL_ERROR, PG::Constants::PGRES_POLLING_FAILED, PG::Constants::PGRES_POLLING_OK, PG::Constants::PGRES_POLLING_READING, PG::Constants::PGRES_POLLING_WRITING, PG::Constants::PGRES_SINGLE_TUPLE, PG::Constants::PGRES_TUPLES_OK, PG::Constants::PG_DIAG_COLUMN_NAME, PG::Constants::PG_DIAG_CONSTRAINT_NAME, PG::Constants::PG_DIAG_CONTEXT, PG::Constants::PG_DIAG_DATATYPE_NAME, PG::Constants::PG_DIAG_INTERNAL_POSITION, PG::Constants::PG_DIAG_INTERNAL_QUERY, PG::Constants::PG_DIAG_MESSAGE_DETAIL, PG::Constants::PG_DIAG_MESSAGE_HINT, PG::Constants::PG_DIAG_MESSAGE_PRIMARY, PG::Constants::PG_DIAG_SCHEMA_NAME, PG::Constants::PG_DIAG_SEVERITY, PG::Constants::PG_DIAG_SOURCE_FILE, PG::Constants::PG_DIAG_SOURCE_FUNCTION, PG::Constants::PG_DIAG_SOURCE_LINE, PG::Constants::PG_DIAG_SQLSTATE, PG::Constants::PG_DIAG_STATEMENT_POSITION, PG::Constants::PG_DIAG_TABLE_NAME, PG::Constants::PQERRORS_DEFAULT, PG::Constants::PQERRORS_TERSE, PG::Constants::PQERRORS_VERBOSE, PG::Constants::PQPING_NO_ATTEMPT, PG::Constants::PQPING_NO_RESPONSE, PG::Constants::PQPING_OK, PG::Constants::PQPING_REJECT, PG::Constants::PQTRANS_ACTIVE, PG::Constants::PQTRANS_IDLE, PG::Constants::PQTRANS_INERROR, PG::Constants::PQTRANS_INTRANS, PG::Constants::PQTRANS_UNKNOWN, PG::Constants::SEEK_CUR, PG::Constants::SEEK_END, PG::Constants::SEEK_SET

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initializeObject

call-seq:

PG::Connection.new -> conn
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.



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# File 'ext/pg_connection.c', line 264

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);
  }

#ifdef M17N_SUPPORTED
  pgconn_set_default_encoding( self );
#endif

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

Class Method Details

.conndefaultsObject

call-seq:

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



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# File 'ext/pg_connection.c', line 397

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

  PQconninfoFree(options);

  UNUSED( self );

  return array;
}

.conndefaults_hashObject

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

See also #conndefaults



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# File 'lib/pg/connection.rb', line 201

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) ⇒ Object .PG::Connection.connect_start(connection_string) ⇒ Object .PG::Connection.connect_start(host, port, options, tty, dbname, login, password) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 310

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

This function is intended to be used by client applications that send commands like: ALTER USER joe PASSWORD 'pwd'. The arguments are the cleartext password, and the SQL name of the user it is for.

Return value is the encrypted password.



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# File 'ext/pg_connection.c', line 422

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

Connection instance method for versions of 8.1 and higher of libpq uses PQescapeByteaConn, which is safer. Avoid calling as a class method, the class method uses the deprecated PQescapeBytea() API function.

Use the instance method version of this function, it is safer than the class method.

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.



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# File 'ext/pg_connection.c', line 1579

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_class(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

Connection instance method for versions of 8.1 and higher of libpq uses PQescapeStringConn, which is safer. Avoid calling as a class method, the class method uses the deprecated PQescapeString() API function.

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.



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# File 'ext/pg_connection.c', line 1526

static VALUE
pgconn_s_escape(VALUE self, VALUE string)
{
  char *escaped;
  size_t size;
  int error;
  VALUE result;

  Check_Type(string, T_STRING);

  escaped = ALLOC_N(char, RSTRING_LEN(string) * 2 + 1);
  if(rb_obj_class(self) == rb_cPGconn) {
    size = PQescapeStringConn(pg_get_pgconn(self), escaped,
      RSTRING_PTR(string), RSTRING_LEN(string), &error);
    if(error) {
      xfree(escaped);
      rb_raise(rb_ePGerror, "%s", PQerrorMessage(pg_get_pgconn(self)));
    }
  } else {
    size = PQescapeString(escaped, RSTRING_PTR(string), RSTRING_LENINT(string));
  }
  result = rb_str_new(escaped, size);
  xfree(escaped);
  OBJ_INFECT(result, string);
  PG_ENCODING_SET_NOCHECK(result, ENCODING_GET( rb_obj_class(self) == rb_cPGconn ? self : string ));

  return result;
}

.parse_connect_args(*args) ⇒ Object

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



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# File 'lib/pg/connection.rb', line 35

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, URI.regexp
      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) ⇒ Fixnum .PG::Connection.ping(connection_string) ⇒ Fixnum .PG::Connection.ping(host, port, options, tty, dbname, login, password) ⇒ Fixnum

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)



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# File 'ext/pg_connection.c', line 361

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) ⇒ Object

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



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# File 'lib/pg/connection.rb', line 28

def self::quote_connstr( value )
  return "'" + value.to_s.gsub( /[\\']/ ) {|m| '\\' + m } + "'"
end

.PG::Connection.quote_ident(str) ⇒ String .PG::Connection.quote_ident(array) ⇒ String .quote_ident(str) ⇒ String .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 PG::Connection.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 .



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# File 'ext/pg_connection.c', line 3027

static VALUE
pgconn_s_quote_ident(VALUE self, VALUE in_str)
{
  VALUE ret;
  pg_text_enc_identifier(NULL, in_str, NULL, &ret);

  OBJ_INFECT(ret, in_str);
  PG_ENCODING_SET_NOCHECK(ret, ENCODING_GET( rb_obj_class(self) == rb_cPGconn ? self : in_str ));

  return ret;
}

.PG::Connection.unescape_bytea(string) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 1612

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;
}

Instance Method Details

#async_exec(sql[, params, result_format ]) ⇒ PG::Result #async_exec(sql[, params, result_format ]) {|pg_result| ... } ⇒ Object Also known as: async_query

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

Overloads:

  • #async_exec(sql[, params, result_format ]) {|pg_result| ... } ⇒ Object

    Yields:

    • (pg_result)


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# File 'ext/pg_connection.c', line 3141

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;
}

#backend_pidFixnum

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



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# File 'ext/pg_connection.c', line 879

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

#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.



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# File 'ext/pg_connection.c', line 3060

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;
}

#cancelString

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.



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# File 'ext/pg_connection.c', line 2177

static VALUE
pgconn_cancel(VALUE self)
{
#ifdef HAVE_PQGETCANCEL
  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;
#else
  rb_notimplement();
#endif
}

#conndefaultsObject

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



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# File 'lib/pg/connection.rb', line 193

def conndefaults
  return self.class.conndefaults
end

#conndefaults_hashObject

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



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# File 'lib/pg/connection.rb', line 209

def conndefaults_hash
  return self.class.conndefaults_hash
end

#connect_pollFixnum

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.


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# File 'ext/pg_connection.c', line 482

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

#connection_needs_passwordBoolean

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



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# File 'ext/pg_connection.c', line 892

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

#connection_used_passwordBoolean

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



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# File 'ext/pg_connection.c', line 905

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

#conninfoHash

Returns the connection options used by a live connection.



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# File 'ext/pg_connection.c', line 680

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_hashObject

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

See also #conninfo



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# File 'lib/pg/connection.rb', line 220

def conninfo_hash
  return self.conninfo.each_with_object({}) do |info, hash|
    hash[ info[:keyword].to_sym ] = info[:val]
  end
end

#consume_inputObject

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.



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# File 'ext/pg_connection.c', line 2059

static VALUE
pgconn_consume_input(self)
VALUE self;

#copy_data(sql, coder = nil) ⇒ Object

call-seq:

conn.copy_data( sql ) {|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.

Example with CSV input format:

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

This creates my_table and inserts two rows.

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


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# File 'lib/pg/connection.rb', line 129

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.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

#dbObject

Returns the connected database name.



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# File 'ext/pg_connection.c', line 580

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_dataPG::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.



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# File 'ext/pg_connection.c', line 3759

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) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 3730

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;
}

#describe_portal(portal_name) ⇒ PG::Result

Retrieve information about the portal portal_name.



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# File 'ext/pg_connection.c', line 1458

static VALUE
pgconn_describe_portal(self, stmt_name)
VALUE self, stmt_name;

#describe_prepared(statement_name) ⇒ PG::Result

Retrieve information about the prepared statement statement_name.



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# File 'ext/pg_connection.c', line 1431

static VALUE
pgconn_describe_prepared(VALUE self, VALUE stmt_name)
{
  PGresult *result;
  VALUE rb_pgresult;
  PGconn *conn = pg_get_pgconn(self);
  char *stmt;
  if(stmt_name == Qnil) {
    stmt = NULL;
  }
  else {
    Check_Type(stmt_name, T_STRING);
    stmt = StringValueCStr(stmt_name);
  }
  result = gvl_PQdescribePrepared(conn, stmt);
  rb_pgresult = pg_new_result(result, self);
  pg_result_check(rb_pgresult);
  return rb_pgresult;
}

#encoder_for_put_copy_dataPG::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, returned data will be a String.



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# File 'ext/pg_connection.c', line 3710

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) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 3681

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;
}

#error_messageString

Returns the error message about connection.



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# File 'ext/pg_connection.c', line 788

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_bytea(string) ⇒ String

Connection instance method for versions of 8.1 and higher of libpq uses PQescapeByteaConn, which is safer. Avoid calling as a class method, the class method uses the deprecated PQescapeBytea() API function.

Use the instance method version of this function, it is safer than the class method.

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.



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# File 'ext/pg_connection.c', line 1579

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_class(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

Escape an arbitrary String str as an identifier.

This method does the same as #quote_ident, but uses libpq to process the string.



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# File 'ext/pg_connection.c', line 1676

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

  Check_Type(string, T_STRING);

  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, ENCODING_GET(self));

  return result;
}

#escape_literal(str) ⇒ String

Escape an arbitrary String str as a literal.



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# File 'ext/pg_connection.c', line 1639

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

  Check_Type(string, T_STRING);

  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, ENCODING_GET(self));

  return result;
}

#escape_string(str) ⇒ String Also known as: escape

Connection instance method for versions of 8.1 and higher of libpq uses PQescapeStringConn, which is safer. Avoid calling as a class method, the class method uses the deprecated PQescapeString() API function.

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.



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# File 'ext/pg_connection.c', line 1526

static VALUE
pgconn_s_escape(VALUE self, VALUE string)
{
  char *escaped;
  size_t size;
  int error;
  VALUE result;

  Check_Type(string, T_STRING);

  escaped = ALLOC_N(char, RSTRING_LEN(string) * 2 + 1);
  if(rb_obj_class(self) == rb_cPGconn) {
    size = PQescapeStringConn(pg_get_pgconn(self), escaped,
      RSTRING_PTR(string), RSTRING_LEN(string), &error);
    if(error) {
      xfree(escaped);
      rb_raise(rb_ePGerror, "%s", PQerrorMessage(pg_get_pgconn(self)));
    }
  } else {
    size = PQescapeString(escaped, RSTRING_PTR(string), RSTRING_LENINT(string));
  }
  result = rb_str_new(escaped, size);
  xfree(escaped);
  OBJ_INFECT(result, string);
  PG_ENCODING_SET_NOCHECK(result, ENCODING_GET( rb_obj_class(self) == rb_cPGconn ? self : string ));

  return result;
}

#exec(sql) ⇒ PG::Result #exec(sql) {|pg_result| ... } ⇒ Object Also known as: query

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.

Overloads:

  • #exec(sql) {|pg_result| ... } ⇒ Object

    Yields:

    • (pg_result)


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# File 'ext/pg_connection.c', line 941

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 ) {
    Check_Type(argv[0], T_STRING);

    result = gvl_PQexec(conn, StringValueCStr(argv[0]));
    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 );
  }

}

#exec_params(sql, params[, result_format[, type_map]]) ⇒ PG::Result #exec_params(sql, params[, result_format[, type_map]]) {|pg_result| ... } ⇒ Object

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   => Fixnum (oid of type of bind parameter)
   :format => Fixnum (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 form 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.

Overloads:

  • #exec_params(sql, params[, result_format[, type_map]]) {|pg_result| ... } ⇒ Object

    Yields:

    • (pg_result)


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# File 'ext/pg_connection.c', line 1252

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;

  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, StringValueCStr(command), 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 #exec_prepared(statement_name[, params, result_format[, type_map]]) {|pg_result| ... } ⇒ Object

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 => Fixnum (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 form 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.

Overloads:

  • #exec_prepared(statement_name[, params, result_format[, type_map]]) {|pg_result| ... } ⇒ Object

    Yields:

    • (pg_result)


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# File 'ext/pg_connection.c', line 1386

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;

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

  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, StringValueCStr(name), 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;
}

#external_encodingEncoding

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



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# File 'ext/pg_connection.c', line 3539

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;
}

#finishObject Also known as: close

Closes the backend connection.



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# File 'ext/pg_connection.c', line 496

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;
}

#finished?Boolean

Returns true if the backend connection has been closed.



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# File 'ext/pg_connection.c', line 514

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

#flushBoolean

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.



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# File 'ext/pg_connection.c', line 2151

static VALUE
pgconn_flush(self)
VALUE self;

#get_client_encodingString

Returns the client encoding as a String.



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# File 'ext/pg_connection.c', line 2922

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 ]]) ⇒ 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 as Array of Strings. Optionally the decoder can type cast the fields to various Ruby types in one step, if PG::TextDecoder::CopyRow#type_map is set accordingly.

See also #copy_data.



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# File 'ext/pg_connection.c', line 2649

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_resultPG::Result

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.



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# File 'ext/pg_connection.c', line 3104

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_resultPG::Result #get_result {|pg_result| ... } ⇒ Object

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.

Overloads:

  • #get_result {|pg_result| ... } ⇒ Object

    Yields:

    • (pg_result)


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# File 'ext/pg_connection.c', line 2033

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;
}

#hostObject

Returns the connected server name.



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# File 'ext/pg_connection.c', line 622

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

#internal_encodingEncoding

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'



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# File 'ext/pg_connection.c', line 3472

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) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 3499

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 ( 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_busyBoolean

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



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# File 'ext/pg_connection.c', line 2081

static VALUE
pgconn_is_busy(self)
VALUE self;

#isnonblockingBoolean Also known as: nonblocking?

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



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# File 'ext/pg_connection.c', line 2134

static VALUE
pgconn_isnonblocking(self)
VALUE self;

#lo_close(lo_desc) ⇒ nil Also known as: loclose

Closes the postgres large object of lo_desc.



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# File 'ext/pg_connection.c', line 3421

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;
}

#lo_creat([mode]) ⇒ Fixnum Also known as: locreat

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



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# File 'ext/pg_connection.c', line 3171

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);
}

#lo_create(oid) ⇒ Fixnum Also known as: locreate

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



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# File 'ext/pg_connection.c', line 3198

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);
}

#lo_export(oid, file) ⇒ nil Also known as: loexport

Saves a large object of oid to a file.



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# File 'ext/pg_connection.c', line 3242

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;
}

#lo_import(file) ⇒ Fixnum Also known as: loimport

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

On failure, it raises a PG::Error.



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# File 'ext/pg_connection.c', line 3220

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);
}

#lo_lseek(lo_desc, offset, whence) ⇒ Fixnum Also known as: lolseek, lo_seek, loseek

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.)



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# File 'ext/pg_connection.c', line 3363

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);
}

#lo_open(oid, [mode]) ⇒ Fixnum Also known as: loopen

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.



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# File 'ext/pg_connection.c', line 3267

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);
}

#lo_read(lo_desc, len) ⇒ String Also known as: loread

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



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# File 'ext/pg_connection.c', line 3322

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;
}

#lo_tell(lo_desc) ⇒ Fixnum Also known as: lotell

Returns the current position of the large object lo_desc.



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# File 'ext/pg_connection.c', line 3383

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);
}

#lo_truncate(lo_desc, len) ⇒ nil Also known as: lotruncate

Truncates the large object lo_desc to size len.



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# File 'ext/pg_connection.c', line 3402

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;
}

Unlinks (deletes) the postgres large object of oid.



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# File 'ext/pg_connection.c', line 3439

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;
}

#lo_write(lo_desc, buffer) ⇒ Fixnum Also known as: lowrite

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



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# File 'ext/pg_connection.c', line 3295

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);
}

#make_empty_pgresult(status) ⇒ PG::Result

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



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# File 'ext/pg_connection.c', line 1496

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;
}

#notifiesObject

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



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# File 'ext/pg_connection.c', line 2211

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;
}

#optionsObject

Returns backend option string.



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# File 'ext/pg_connection.c', line 663

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

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.



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# File 'ext/pg_connection.c', line 741

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);
}

#passObject

Returns the authenticated user name.



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# File 'ext/pg_connection.c', line 608

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

#portObject

Returns the connected server port number.



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# File 'ext/pg_connection.c', line 636

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

#prepare(stmt_name, sql[, param_types ]) ⇒ PG::Result

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.



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# File 'ext/pg_connection.c', line 1313

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;

  rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
  Check_Type(name, T_STRING);
  Check_Type(command, T_STRING);

  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, StringValueCStr(name), StringValueCStr(command),
      nParams, paramTypes);

  xfree(paramTypes);

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

#protocol_versionInteger

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.)



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# File 'ext/pg_connection.c', line 759

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

#put_copy_data(buffer[, encoder]) ⇒ Boolean

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 received data fields from an Array of Strings. Optionally the encoder can type cast the fields form various Ruby types in one step, if PG::TextEncoder::CopyRow#type_map is set accordingly.

Raises an exception if an error occurs.

See also #copy_data.



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# File 'ext/pg_connection.c', line 2539

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;

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

    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);
      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

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).



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# File 'ext/pg_connection.c', line 2610

static VALUE
pgconn_put_copy_end(int argc, VALUE *argv, VALUE self)
{
  VALUE str;
  VALUE error;
  int ret;
  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 = StringValueCStr(str);

  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;
}

#PG::Connection.quote_ident(str) ⇒ String #PG::Connection.quote_ident(array) ⇒ String #quote_ident(str) ⇒ String #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 PG::Connection.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 .



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# File 'ext/pg_connection.c', line 3027

static VALUE
pgconn_s_quote_ident(VALUE self, VALUE in_str)
{
  VALUE ret;
  pg_text_enc_identifier(NULL, in_str, NULL, &ret);

  OBJ_INFECT(ret, in_str);
  PG_ENCODING_SET_NOCHECK(ret, ENCODING_GET( rb_obj_class(self) == rb_cPGconn ? self : in_str ));

  return ret;
}

#resetObject

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



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# File 'ext/pg_connection.c', line 530

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

#reset_pollFixnum

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



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# File 'ext/pg_connection.c', line 565

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

#reset_startnil

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.



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# File 'ext/pg_connection.c', line 548

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

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



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# File 'ext/pg_connection.c', line 2002

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,StringValueCStr(portal)) == 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

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



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# File 'ext/pg_connection.c', line 1980

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,StringValueCStr(stmt_name)) == 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

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.



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# File 'ext/pg_connection.c', line 1862

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;

  rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
  Check_Type(name, T_STRING);
  Check_Type(command, T_STRING);

  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, StringValueCStr(name), StringValueCStr(command),
      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[, 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   => Fixnum (oid of type of bind parameter)
   :format => Fixnum (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 form 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.



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# File 'ext/pg_connection.c', line 1796

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;

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

  /* If called with no parameters, use PQsendQuery */
  if(NIL_P(paramsData.params)) {
    if(gvl_PQsendQuery(conn,StringValueCStr(command)) == 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, StringValueCStr(command), 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 ]]) ⇒ Object #-Object

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 => Fixnum (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 form 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.



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# File 'ext/pg_connection.c', line 1935

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;

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

  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, StringValueCStr(name), 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_versionInteger

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.



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# File 'ext/pg_connection.c', line 776

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

#set_client_encoding(encoding) ⇒ Object Also known as: client_encoding=

Sets the client encoding to the encoding String.



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# File 'ext/pg_connection.c', line 2936

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

  Check_Type(str, T_STRING);

  if ( (PQsetClientEncoding(conn, StringValueCStr(str))) == -1 ) {
    rb_raise(rb_ePGerror, "invalid encoding name: %s",StringValueCStr(str));
  }
#ifdef M17N_SUPPORTED
  pgconn_set_internal_encoding_index( self );
#endif

  return Qnil;
}

#set_default_encodingEncoding

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.



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# File 'ext/pg_connection.c', line 3566

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 ( PQsetClientEncoding(conn, 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;
  }
}

#set_error_verbosity(verbosity) ⇒ Fixnum

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

  • PQERRORS_TERSE

  • PQERRORS_DEFAULT

  • PQERRORS_VERBOSE



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# File 'ext/pg_connection.c', line 2708

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

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.

Yields:

  • (message)


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# File 'ext/pg_connection.c', line 2887

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

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.

Yields:

  • (result)


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# File 'ext/pg_connection.c', line 2827

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_modeself

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 Connection#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


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# File 'ext/pg_connection.c', line 1741

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

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.



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# File 'ext/pg_connection.c', line 2104

static VALUE
pgconn_setnonblocking(self, state)
VALUE self, state;

#socketFixnum

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 really usable, since it can not be used to build a Ruby IO object.



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# File 'ext/pg_connection.c', line 811

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_ioObject

Fetch a memoized 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.

This method can also be used on Windows but requires Ruby-2.0+.



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# File 'ext/pg_connection.c', line 837

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, when supported */
    if( rb_respond_to(socket_io, id_autoclose) ){
      rb_funcall( socket_io, id_autoclose, 1, Qfalse );
    }

    this->socket_io = socket_io;
  }

  return socket_io;
}

#statusObject

Returns status of connection : CONNECTION_OK or CONNECTION_BAD



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# File 'ext/pg_connection.c', line 700

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

#trace(stream) ⇒ nil

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.



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# File 'ext/pg_connection.c', line 2725

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| ... } ⇒ Object

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

Yields:

  • (conn)


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# File 'ext/pg_connection.c', line 2961

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_statusObject

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)


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# File 'ext/pg_connection.c', line 717

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

#ttyObject

Returns the connected pgtty. (Obsolete)



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# File 'ext/pg_connection.c', line 649

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_queriesTypeMap

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



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# File 'ext/pg_connection.c', line 3621

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) ⇒ Object

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

typemap must be a kind of PG::TypeMap .



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# File 'ext/pg_connection.c', line 3598

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_resultsTypeMap

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



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# File 'ext/pg_connection.c', line 3660

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) ⇒ Object

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

typemap must be a kind of PG::TypeMap .



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# File 'ext/pg_connection.c', line 3638

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) ⇒ Object

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.



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# File 'ext/pg_connection.c', line 1612

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;
}

#untracenil

Disables the message tracing.



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# File 'ext/pg_connection.c', line 2767

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;
}

#userObject

Returns the authenticated user name.



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# File 'ext/pg_connection.c', line 594

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 ]) ⇒ String #wait_for_notify([ timeout ]) {|event, pid| ... } ⇒ Object #wait_for_notify([ timeout ]) ⇒ Object Also known as: notifies_wait

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 and the generating pid into the block.

Under PostgreSQL 9.0 and later, if the notification is sent with the optional payload string, it will be given to the block as the third argument.

Overloads:

  • #wait_for_notify([ timeout ]) {|event, pid| ... } ⇒ Object

    Yields:

    • (event, pid)


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# File 'ext/pg_connection.c', line 2478

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 );
#ifdef HAVE_ST_NOTIFY_EXTRA
  if ( *pnotification->extra ) {
    extra = rb_tainted_str_new2( pnotification->extra );
    PG_ENCODING_SET_NOCHECK( extra, ENCODING_GET(self) );
  }
#endif
  PQfreemem( pnotification );

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

  return relname;
}