wp-trac-39254.php

<?php
/**
 * Plugin Name: WP Trac #39254: Allow starter content posts to display in The Loop
 * Version: 0.1.0
 * Author: Weston Ruter, XWP
 * Plugin URI: https://core.trac.wordpress.org/ticket/39254
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2 or, at
 * your discretion, any later version, as published by the Free
 * Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * @package WordPress
 */

/**
 * Class WP_Trac_39254
 *
 * The methods in this class would likely go into `WP_Customize_Nav_Menus`,
 * perhaps replacing the `make_auto_draft_status_previewable` method.
 *
 * @see WP_Customize_Nav_Menus::make_auto_draft_status_previewable()
 */
class WP_Trac_39254 {

	/**
	 * Auto draft post IDs in the current changeset.
	 *
	 * @var array
	 */
	protected $changeset_auto_draft_post_ids = array();

	/**
	 * Constructor.
	 */
	function __construct() {
		add_action( 'customize_preview_init', array( $this, 'make_auto_draft_post_stubs_queryable' ) );
	}

	/**
	 * Add hooks to ensure auto-draft posts from the current changeset are included in WP_Query results.
	 *
	 * @param WP_Customize_Manager $wp_customize Manager.
	 */
	function make_auto_draft_post_stubs_queryable( WP_Customize_Manager $wp_customize ) {
		global $wp_post_statuses;

		// WordPress 4.7 required.
		if ( ! method_exists( $wp_customize, 'changeset_data' ) ) {
			return;
		}

		/*
		 * Note that we cannot use $wp_customize->get_setting( 'nav_menus_created_posts' )->value()
		 * for the sake of unauthenticated users who may be previewing the changeset on the
		 * frontend. The WP_Customize_Nav_Menus::sanitize_nav_menus_created_posts() function
		 * removes IDs from the list for which the current user cannot edit.
		 */
		$changeset_data = $wp_customize->changeset_data();
		if ( isset( $changeset_data['nav_menus_created_posts']['value'] ) && is_array( $changeset_data['nav_menus_created_posts']['value'] ) ) {
			$this->changeset_auto_draft_post_ids = array_merge(
				$this->changeset_auto_draft_post_ids,
				$changeset_data['nav_menus_created_posts']['value']
			);
		}

		/*
		 * Now merge the starter content post IDs  from the changeset with any additional
		 * IDs for page/post stubs created for nav menus which may not have been written
		 * into the changeset yet (which are still being sent in POST data).
		 */
		$nav_menus_created_posts_setting = $wp_customize->get_setting( 'nav_menus_created_posts' );
		if ( $nav_menus_created_posts_setting ) {
			$this->changeset_auto_draft_post_ids = array_merge(
				$this->changeset_auto_draft_post_ids,
				$nav_menus_created_posts_setting->value()
			);
		}

		// If there are no auto-draft posts in the current changeset, then there is nothing to do here.
		if ( empty( $this->changeset_auto_draft_post_ids ) ) {
			return;
		}

		/*
		 * Ensure that starter content posts (with auto-draft status) will be considered
		 * to have a public post status in in WP_Query::get_posts(), at:
		 * https://github.com/WordPress/wordpress-develop/blob/4.7.3/src/wp-includes/class-wp-query.php#L2351-L2357
		 * Compare this with WP_Customize_Nav_Menus::make_auto_draft_status_previewable(),
		 * which apparently did not go far enough.
		 */
		$wp_post_statuses['auto-draft']->public = true;

		add_action( 'pre_get_posts', array( $this, 'prevent_filter_suppression' ), 100, 2 );
		add_filter( 'posts_where', array( $this, 'filter_posts_where_to_include_post_stubs' ) );
	}

	/**
	 * Make sure that the posts_where filter will be applied.
	 *
	 * @param WP_Query $query The WP_Query instance.
	 */
	function prevent_filter_suppression( WP_Query $query ) {
		$query->set( 'suppress_filters', false );
	}

	/**
	 * Filter SQL WHERE clause for posts queries to exclude auto-draft posts that aren't part of the current changeset.
	 *
	 * @param string $where The WHERE clause of the query.
	 * @return string Amended SQL WHERE.
	 */
	function filter_posts_where_to_include_post_stubs( $where ) {
		global $wpdb;

		/*
		 * This could be improved if WP_Query::get_posts() would allow for the
		 * post statuses to be queried to be individually filtered before it is
		 * added to the WHERE string for filtering. Perhaps there could be a
		 * `posts_where_statuses` filter which was passed an array of the
		 * conditions before they are AND'ed together.
		 * See https://github.com/WordPress/wordpress-develop/blob/4.7.3/src/wp-includes/class-wp-query.php#L2289-L2376
		 */
		$old_condition = "{$wpdb->posts}.post_status = 'publish'";

		$new_condition = "( $old_condition OR ( ";
		$new_condition .= "{$wpdb->posts}.post_status = 'auto-draft' ";
		$new_condition .= ' AND ';
		$new_condition .= sprintf(
			"{$wpdb->posts}.ID IN ( %s )",
			join( ', ', array_map( 'intval', $this->changeset_auto_draft_post_ids ) )
		);
		$new_condition .= '))';

		// @todo This is somewhat brittle.
		$where = str_replace( $old_condition, $new_condition, $where );

		return $where;
	}
}

$wp_trac_39254_plugin = new WP_Trac_39254();