Vala PostgreSQL Example
/**
* To compile:
* valac --pkg libpq test.vala -X -lpq
*/
using GLib;
using Postgres;
public static int main (string[] args)
{
string conninfo;
if (args.length > 1) {
conninfo = args[1];
} else {
conninfo = "dbname = postgres";
}
/* Make a connection to the database */
Database conn = Postgres.connect_db (conninfo);
/* Check to see that the backend connection was successfully made */
if (conn.get_status () != ConnectionStatus.OK) {
stderr.printf ("Connection to database failed: %s", conn.get_error_message ());
return 1;
}
/*
* 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 */
Result res = conn.exec ("BEGIN");
if (res.get_status () != ExecStatus.COMMAND_OK) {
stderr.printf ("BEGIN command failed: %s", conn.get_error_message ());
return 1;
}
/*
* Fetch rows from pg_database, the system catalog of databases
*/
res = conn.exec ("DECLARE myportal CURSOR FOR select * from pg_database");
if (res.get_status () != ExecStatus.COMMAND_OK) {
stderr.printf ("DECLARE CURSOR failed: %s", conn.get_error_message ());
return 1;
}
res = conn.exec ("FETCH ALL in myportal");
if (res.get_status () != ExecStatus.TUPLES_OK) {
stderr.printf ("FETCH ALL failed: %s", conn.get_error_message ());
return 1;
}
/* first, print out the attribute names */
int nFields = res.get_n_fields ();
for (int i = 0; i < nFields; i++) {
stdout.printf ("%-15s", res.get_field_name (i));
}
stdout.printf ("\n\n");
/* next, print out the rows */
for (int i = 0; i < res.get_n_tuples(); i++) {
for (int j = 0; j < nFields; j++) {
stdout.printf ("%-15s", res.get_value (i, j));
}
stdout.printf ("\n");
}
ConnectionOptions opt = Postgres.get_default_options ();
stdout.printf ("label=%s, keyword=%s\n", opt.label, opt.keyword);
stdout.printf ("db=%s, user=%s, passwd=%s, host=%s, port=%s, tty=%s, options=%s\n", conn.get_db (), conn.get_user (), conn.get_passwd (), conn.get_host (), conn.get_port (), conn.get_tty (), conn.get_options ());
/* close the portal ... we don't bother to check for errors ... */
res = conn.exec ("CLOSE myportal");
/* end the transaction */
res = conn.exec ("END");
return 0;
}