libpq93_bindings 0.0.1

PostgreSQL 9.3 database bindings to "libpq" library for Dart.

example/example.dart

import 'dart:io';
import 'package:binary_interop/binary_interop.dart';
import 'package:libc/headers.dart';
import 'package:libpq93_bindings/headers.dart';
import 'package:libpq93_bindings/libpq93_bindings.dart';

/**
 * Example 31-1. libpq Example Program 1
 * 
 * http://www.postgresql.org/docs/9.1/static/libpq-example.html * 
 */
void main(List<String> args) {
  var t = new BinaryTypes();
  var h = new BinaryTypeHelper(t);
  h.addHeaders(LIBC_HEADERS);
  h.addHeaders(LIBPQ93_HEADERS);
  var libpq = loadLibpq93Library(t);
  var conninfo = "dbname = postgres";
  if (args.length == 2) {
    var user = args[0];
    var pass = args[1];
    conninfo += " user=$user password=$pass";
  }

  /* Make a connection to the database */
  var conn = libpq.PQconnectdb(conninfo);

  /* Check to see that the backend connection was successfully made */
  if (libpq.PQstatus(conn) != Libpq93Def.CONNECTION_OK) {
    var message = h.readString(libpq.PQerrorMessage(conn));
    print("Connection to database failed: $message");
    exit_nicely(libpq, conn);
  }

  /*
   * Our test case here involves using a cursor, for which we must be inside
   * a transaction block.  We could do the whole thing with a single
   * PQexec() of "select * from pg_database", but that's too trivial to make
   * a good example.
   */

  /* Start a transaction block */
  var res = libpq.PQexec(conn, "BEGIN");
  if (libpq.PQresultStatus(res) != Libpq93Def.PGRES_COMMAND_OK) {
    var message = h.readString(libpq.PQerrorMessage(conn));
    print("BEGIN command failed: $message");
    libpq.PQclear(res);
    exit_nicely(libpq, conn);
  }

  /*
   * Should PQclear PGresult whenever it is no longer needed to avoid memory
   * leaks
   */
  libpq.PQclear(res);

  /*
   * Fetch rows from pg_database, the system catalog of databases
   */
  res = libpq.PQexec(
      conn, "DECLARE myportal CURSOR FOR select * from pg_database");
  if (libpq.PQresultStatus(res) != Libpq93Def.PGRES_COMMAND_OK) {
    var message = h.readString(libpq.PQerrorMessage(conn));
    print("DECLARE CURSOR failed: $message");
    libpq.PQclear(res);
    exit_nicely(libpq, conn);
  }

  libpq.PQclear(res);

  res = libpq.PQexec(conn, "FETCH ALL in myportal");
  if (libpq.PQresultStatus(res) != Libpq93Def.PGRES_TUPLES_OK) {
    var message = h.readString(libpq.PQerrorMessage(conn));
    print("FETCH ALL failed: $message");
    libpq.PQclear(res);
    exit_nicely(libpq, conn);
  }

  /* first, print out the attribute names */
  var nFields = libpq.PQnfields(res);
  for (var i = 0; i < nFields; i++) {
    var value = h.readString(libpq.PQfname(res, i));
    print(value);
  }

  print("\n");

  /* next, print out the rows */
  for (var i = 0; i < libpq.PQntuples(res); i++) {
    for (var j = 0; j < nFields; j++) {
      var value = h.readString(libpq.PQgetvalue(res, i, j));
      print(value);
    }

    print("");
  }

  libpq.PQclear(res);

  /* close the portal ... we don't bother to check for errors ... */
  res = libpq.PQexec(conn, "CLOSE myportal");
  libpq.PQclear(res);

  /* end the transaction */
  res = libpq.PQexec(conn, "END");
  libpq.PQclear(res);

  /* close the connection to the database and cleanup */
  libpq.PQfinish(conn);
}

exit_nicely(Libpq93Lib libpq, BinaryData conn) {
  libpq.PQfinish(conn);
  exit(1);
}