public function detect_by_id( $post = null ) {

		// only the rsvp order key is non numeric
		if ( is_object( $post ) && ! empty( $post->ID ) ) {
			$cpt  = get_post_type( $post->ID );
			$post = (int) $post->ID;
		} elseif ( ! is_numeric( $post ) ) {
			$post = esc_attr( $post );
			$cpt  = $this->check_rsvp_order_key_exists( $post );
		} else {
			$post = absint( $post );
			$cpt  = get_post_type( $post );
		}

		// if no custom post type
		if ( ! $cpt ) {
			return false;
		}

		$cpt_arr              = array();
		$cpt_arr['post_type'] = $cpt;

		foreach ( $this->ticket_types as $type => $cpts ) {
			if ( in_array( $cpt, $cpts ) ) {
				$cpt_arr[] = $type;
			}
		}

		foreach ( $this->ticket_class as $classes => $cpts ) {
			if ( in_array( $cpt, $cpts ) ) {
				$cpt_arr['class'] = $classes;
			}
		}

		return $cpt_arr;
	}