pg_result_error_field - PHP code example

PHP Function pg_result_error_field()

The php function pg_result_error_field() returns an individual field of the error message associated with a result resource. The function is only available against a PostgreSQL 7.4 or higher server. It can provide more detailed error information than the string returned by pg_last_error(). The error field is identified by a parameter called fieldcode. Possible fieldcode values are: PGSQL_DIAG_SEVERITY, PGSQL_DIAG_SQLSTATE, PGSQL_DIAG_MESSAGE_PRIMARY, PGSQL_DIAG_MESSAGE_DETAIL, PGSQL_DIAG_HINT or PGSQL_DIAG_CONTEXT.

The function is useful when the error message of a failed pg_query() query cannot be determined because it was overwritten by other internal PostgreSQL (libpq) function calls. It is also useful when a database connection is busy or disconnected and it needs to be drained of all results in order to free up resources.

The function pg_result_error_field() is similar to the PQresultErrorField() function introduced in PostgreSQL 7.4. This allows you to get SQLSTATE code from a query, which is far more useful than the error string returned by pg_last_error(). This function uses pg_get_result(), so the result handle must be obtained from a previous call to this function. The function works with PostgreSQL bytea values, so the bytea data must be cast if it is not already in a PHP binary string. This can happen when the client and backend character encoding do not match. For example, when INSERTing a multi-byte string into a table with PostgreSQL 7.2 or later. This is not a problem with older versions of PostgreSQL, which did not support bytea. See the article Using PostgreSQL bytea data with PHP for more information.

pg_result_error_field example

public static function castResult($result, array $a, Stub $stub, bool $isNested)
    {
        $a['num rows'] = pg_num_rows($result);
        $a['status'] = pg_result_status($result);
        if (isset(self::RESULT_STATUS[$a['status']])) {
            $a['status'] = new ConstStub(self::RESULT_STATUS[$a['status']], $a['status']);
        }
        $a['command-completion tag'] = pg_result_status($result, \PGSQL_STATUS_STRING);

        if (-1 === $a['num rows']) {
            foreach (self::DIAG_CODES as $k => $v) {
                $a['error'][$k] = pg_result_error_field($result, $v);
            }
        }

        $a['affected rows'] = pg_affected_rows($result);
        $a['last OID'] = pg_last_oid($result);

        $fields = pg_num_fields($result);

        for ($i = 0; $i < $fields; ++$i) {
            $field = [
                'name' => pg_field_name($result, $i),