protected function _type_assignment_set( $type, $value )
	{
		switch ( $type ) 
		{
			case 'int':
			case 'timestamp':
				return (int) $value;
			break;

			case 'string':
				return (string) $value;
			break;

			case 'bool':
				return (bool) $value;
			break;

			// json datatype simply encode
			case 'json':
				return json_encode( $value );
			break;
		}

		return $value;
	}