Rewrite Rules: Add support for random content redirects.

Introduce a `random` query var and `/random/` rewrite rules[1], built on the existing rewrite, WP, and query APIs, that redirect to a randomly selected published post. Random requests[2] work for the whole site, taxonomy terms, authors and post type archives, with the base configurable on the Permalinks screen. A new `randomable` post type argument controls which content is eligible, and the selection runs through the main query so it remains filterable and costs a single database query.

The Random Base[3] is translatable and stored in the rewrite rules. This means that rewrite rules are regenerated when translations are updated or the Site Language is changed. Also, if a post or page is published that would result in the same slug as the Random Base, that content gets priority and nothing will be random[4].

This reintroduces the feature committed in r63767 and reverted in r63906.

1) Literally `/random/`, not just rules that are random. Though that could be fun too!
2) Not "random" as in unpredictable, but random as in someone wanted it to be random.
3) It's intentionally "random" but it could also intentionally be "aleatoria" or "karkovice".
4) The other random permalinks will still work, so not nothing. But is anything really random?

Developed in: #14018

Follow-up to r63767, r63906.

Props jorbin, peterwilsoncc, westonruter, mukesh27, annezazu, mlaetitia, mcsf, johnbillion, TobiasBg, solankisoftware, sajib1223, ellatrix, matt.
See #64498.


git-svn-id: https://develop.svn.wordpress.org/trunk@64402 602fd350-edb4-49c9-b593-d223f7449a82

Author: aaronjorbin

src/wp-admin/includes/schema.php

@@ -563,6 +563,9 @@ function populate_options( array $options = array() ) {
 
 		// 6.9.0
 		'wp_notes_notify'                 => 1,
+
+		// 7.2.0
+		'wp_random_base'                  => '',
 	);
 
 	// 3.3.0

src/wp-admin/includes/upgrade.php

@@ -2892,7 +2892,7 @@ function __get_option( $setting ) { // phpcs:ignore WordPress.NamingConventions.
 		return __get_option( 'siteurl' );
 	}
 
-	if ( in_array( $setting, array( 'siteurl', 'home', 'category_base', 'tag_base' ), true ) ) {
+	if ( in_array( $setting, array( 'siteurl', 'home', 'category_base', 'tag_base', 'wp_random_base' ), true ) ) {
 		$option = untrailingslashit( $option );
 	}
 

src/wp-admin/network/site-settings.php

@@ -162,6 +162,7 @@
 				'permalink_structure',
 				'category_base',
 				'tag_base',
+				'wp_random_base',
 				'upload_path',
 				'upload_url_path',
 			);

src/wp-admin/options-permalink.php

@@ -69,6 +69,9 @@
 get_current_screen()->set_help_sidebar( $help_sidebar_content );
 unset( $help_sidebar_content );
 
+/** @global WP_Rewrite $wp_rewrite WordPress rewrite component. */
+global $wp_rewrite;
+
 $home_path           = get_home_path();
 $iis7_permalinks     = iis7_supports_permalinks();
 $permalink_structure = get_option( 'permalink_structure' );
@@ -94,6 +97,8 @@
 
 $category_base = get_option( 'category_base' );
 $tag_base      = get_option( 'tag_base' );
+$random_base   = get_option( 'wp_random_base' );
+$random_base   = is_string( $random_base ) ? $random_base : '';
 
 $structure_updated        = false;
 $htaccess_update_required = false;
@@ -144,6 +149,16 @@
 
 		$wp_rewrite->set_tag_base( $tag_base );
 	}
+
+	if ( wp_is_random_content_redirect_enabled() && isset( $_POST['wp_random_base'] ) && is_string( $_POST['wp_random_base'] ) ) {
+		$random_base = $_POST['wp_random_base'];
+
+		if ( ! empty( $random_base ) ) {
+			$random_base = $blog_prefix . preg_replace( '#/+#', '/', '/' . str_replace( '#', '', $random_base ) );
+		}
+
+		$wp_rewrite->set_random_base( $random_base );
+	}
 }
 
 if ( $iis7_permalinks ) {
@@ -236,6 +251,7 @@
 	$permalink_structure = preg_replace( '|^/?blog|', '', $permalink_structure );
 	$category_base       = preg_replace( '|^/?blog|', '', $category_base );
 	$tag_base            = preg_replace( '|^/?blog|', '', $tag_base );
+	$random_base         = preg_replace( '|^/?blog|', '', $random_base ) ?? '';
 }
 
 $url_base = home_url( $blog_prefix . $index_php_prefix );
@@ -457,6 +473,29 @@ class="button button-secondary"
 		<?php endif; ?>
 		</td>
 	</tr>
+	<?php if ( wp_is_random_content_redirect_enabled() ) : ?>
+	<tr>
+		<th>
+			<label for="wp_random_base">
+				<?php _e( 'Random base' ); ?>
+			</label>
+		</th>
+		<td>
+		<?php if ( '' === $blog_prefix ) : ?>
+			<input name="wp_random_base" id="wp_random_base" type="text"
+				value="<?php echo esc_attr( $random_base ); ?>" class="regular-text code"
+			/>
+		<?php else : ?>
+			<span class="code permalink-structure-has-blog-prefix">
+				<code class="no-break"><?php echo $blog_prefix; ?></code>
+				<input name="wp_random_base" id="wp_random_base" type="text"
+					value="<?php echo esc_attr( $random_base ); ?>" class="regular-text code"
+				/>
+			</span>
+		<?php endif; ?>
+		</td>
+	</tr>
+	<?php endif; ?>
 	<?php do_settings_fields( 'permalink', 'optional' ); ?>
 </table>
 

src/wp-includes/class-wp-post-type.php

@@ -123,6 +123,19 @@ final class WP_Post_Type {
 	 */
 	public $embeddable = null;
 
+	/**
+	 * Whether posts of this post type can be selected by random content redirects.
+	 *
+	 * Random content redirects send requests such as `example.com/random/` to a
+	 * randomly selected post.
+	 *
+	 * Default is true when $publicly_queryable is true and the post type has an archive.
+	 *
+	 * @since 7.2.0
+	 * @var bool $randomable
+	 */
+	public $randomable = null;
+
 	/**
 	 * Whether to generate and allow a UI for managing this post type in the admin.
 	 *
@@ -546,6 +559,7 @@ public function set_props( $args ) {
 			'exclude_from_search'             => null,
 			'publicly_queryable'              => null,
 			'embeddable'                      => null,
+			'randomable'                      => null,
 			'show_ui'                         => null,
 			'show_in_menu'                    => null,
 			'show_in_nav_menus'               => null,
@@ -590,6 +604,9 @@ public function set_props( $args ) {
 		// If not set, default to the setting for 'public'.
 		$args['embeddable'] ??= $args['public'];
 
+		// If not set, default to publicly queryable post types with an archive.
+		$args['randomable'] ??= $args['publicly_queryable'] && (bool) $args['has_archive'];
+
 		// If not set, default rest_namespace to wp/v2 if show_in_rest is true.
 		if ( false === $args['rest_namespace'] && ! empty( $args['show_in_rest'] ) ) {
 			$args['rest_namespace'] = 'wp/v2';

src/wp-includes/class-wp-query.php

@@ -417,6 +417,16 @@ class WP_Query {
 	 */
 	public bool $is_sitemap = false;
 
+	/**
+	 * Signifies whether the current query is for random content.
+	 *
+	 * True for a blog home, archive or search request that includes the `random`
+	 * query variable, for example `example.com/random/` or `example.com/?s=foo&random`.
+	 *
+	 * @since 7.2.0
+	 */
+	public bool $is_random = false;
+
 	/**
 	 * Signifies whether the current query is for the page_for_posts page.
 	 *
@@ -527,6 +537,7 @@ private function init_query_flags() {
 		$this->is_robots            = false;
 		$this->is_favicon           = false;
 		$this->is_sitemap           = false;
+		$this->is_random            = false;
 		$this->is_posts_page        = false;
 		$this->is_post_type_archive = false;
 	}
@@ -1147,6 +1158,10 @@ public function parse_query( $query = '' ) {
 
 		$this->is_embed = $this->is_embed && ( $this->is_singular || $this->is_404 );
 
+		$this->is_random = isset( $query_vars['random'] )
+			&& ! $this->is_feed
+			&& ( $this->is_home || $this->is_archive || $this->is_search );
+
 		$this->query_vars_hash    = md5( serialize( $this->query_vars ) );
 		$this->query_vars_changed = false;
 
@@ -4653,6 +4668,19 @@ public function is_sitemap(): bool {
 		return $this->is_sitemap;
 	}
 
+	/**
+	 * Determines whether the query is for random content.
+	 *
+	 * @since 7.2.0
+	 *
+	 * @see wp_is_random_content_query()
+	 *
+	 * @return bool Whether the query is for random content.
+	 */
+	public function is_random(): bool {
+		return $this->is_random;
+	}
+
 	/**
 	 * Determines whether the query is for a search.
 	 *