public function set_fields( array $data ) {
		foreach ( $data as $key => $val ) {
			if ( array_key_exists( $key, $this->_data ) ) {
				if ( is_array( $this->$key ) && is_array( $val ) ) {
					$this->$key = array_replace_recursive( $this->$key, $val );
				} else {
					$this->$key = $val;
				}
			}
		}
	}