Cake\Database\Schema\PostgresSchema::_convertConstraint PHP Метод

    protected function _convertConstraint($table, $name, $type, $row)
    {
        $constraint = $table->constraint($name);
        if (!$constraint) {
            $constraint = ['type' => $type, 'columns' => []];
        }
        $constraint['columns'][] = $row['attname'];
        $table->addConstraint($name, $constraint);
    }