From ba5cc4e7768f40842ba3834e2785699c7fc7488e Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@gmail.com>
Date: Tue, 23 Feb 2016 16:40:26 +0000
Subject: [PATCH] Query: Allow a seed value to be passed when using 'rand'
 `$orderby`.

`WP_Query` allows random ordering; `'orderby' => 'rand'` translates to
`ORDER BY RAND()`. This syntax results in random ordering that is not
consistent from request to request. MySQL supports the passing of a seed value
to random sorts, such as `ORDER BY RAND(3)`, which will return the same
random value each time it's called. `WP_Query` now supports this syntax, by
passing `RAND(3)` (or whatever integer seed value you'd like) as the value
of `'orderby'`.

Props hlashbrooke.
Fixes #35692.
Built from https://develop.svn.wordpress.org/trunk@36632


git-svn-id: http://core.svn.wordpress.org/trunk@36599 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/query.php   | 12 ++++++++++++
 wp-includes/version.php |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/wp-includes/query.php b/wp-includes/query.php
index 70d02378d9..99df782336 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1467,6 +1467,7 @@ class WP_Query {
 	 *              search terms, by prepending a hyphen.
 	 * @since 4.5.0 Removed the `$comments_popup` parameter.
 	 *              Introduced the `$comment_status` and `$ping_status` parameters.
+	 *              Introduced `RAND(x)` syntax for `$orderby`, which allows an integer seed value to random sorts.
 	 * @access public
 	 *
 	 * @param string|array $query {
@@ -1520,6 +1521,7 @@ class WP_Query {
 	 *                                                 specific `$meta_query` clause, use that clause's array key.
 	 *                                                 Default 'date'. Accepts 'none', 'name', 'author', 'date',
 	 *                                                 'title', 'modified', 'menu_order', 'parent', 'ID', 'rand',
+	 *                                                 'RAND(x)' (where 'x' is an integer seed value),
 	 *                                                 'comment_count', 'meta_value', 'meta_value_num', 'post__in',
 	 *                                                 and the array keys of `$meta_query`.
 	 *     @type int          $p                       Post ID.
@@ -2332,6 +2334,14 @@ class WP_Query {
 			$allowed_keys   = array_merge( $allowed_keys, array_keys( $meta_clauses ) );
 		}
 
+		// If RAND() contains a seed value, sanitize and add to allowed keys.
+		$rand_with_seed = false;
+		if ( preg_match( '/RAND\(([0-9]+)\)/i', $orderby, $matches ) ) {
+			$orderby = sprintf( 'RAND(%s)', intval( $matches[1] ) );
+			$allowed_keys[] = $orderby;
+			$rand_with_seed = true;
+		}
+
 		if ( ! in_array( $orderby, $allowed_keys, true ) ) {
 			return false;
 		}
@@ -2368,6 +2378,8 @@ class WP_Query {
 					// $orderby corresponds to a meta_query clause.
 					$meta_clause = $meta_clauses[ $orderby ];
 					$orderby_clause = "CAST({$meta_clause['alias']}.meta_value AS {$meta_clause['cast']})";
+				} elseif ( $rand_with_seed ) {
+					$orderby_clause = $orderby;
 				} else {
 					// Default: order by post field.
 					$orderby_clause = "$wpdb->posts.post_" . sanitize_key( $orderby );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index b8bcdf4990..be2af7e4b6 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.5-alpha-36631';
+$wp_version = '4.5-alpha-36632';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.