From c2a0d593ac2d6107450d874537d96681162ebfd1 Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@gmail.com>
Date: Thu, 8 Oct 2015 03:18:24 +0000
Subject: [PATCH] Allow excluded keywords when searching posts.

Pass a keyword with a leading hyphen to exclude posts containing that keyword.
For example, 'taco -onions' will return posts that contain the word 'taco' but
do not contain the word 'onions'.

Props akibjorklund.
Fixes #33988.
Built from https://develop.svn.wordpress.org/trunk@34934


git-svn-id: http://core.svn.wordpress.org/trunk@34899 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/query.php   | 38 +++++++++++++++++++++++++++++++-------
 wp-includes/version.php |  2 +-
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/wp-includes/query.php b/wp-includes/query.php
index 94e48391d9..f3287dae9d 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1509,7 +1509,8 @@ class WP_Query {
 	 * @since 1.5.0
 	 * @since 4.2.0 Introduced the ability to order by specific clauses of a `$meta_query`, by passing the clause's
 	 *              array key to `$orderby`.
-	 * @since 4.4.0 Introduced `$post_name__in` and `$title` parameters.
+	 * @since 4.4.0 Introduced `$post_name__in` and `$title` parameters. `$s` was updated to support excluded
+	 *              search terms, by prepending a hyphen.
 	 * @access public
 	 *
 	 * @param string|array $query {
@@ -1587,7 +1588,9 @@ class WP_Query {
 	 *     @type int          $posts_per_archive_page  The number of posts to query for by archive page. Overrides
 	 *                                                 'posts_per_page' when is_archive(), or is_search() are true.
 	 *     @type array        $post_name__in           An array of post slugs that results must match.
-	 *     @type string       $s                       Search keyword.
+	 *     @type string       $s                       Search keyword(s). Prepending a term with a hyphen will
+	 *                                                 exclude posts matching that term. Eg, 'pillow -sofa' will
+	 *                                                 return posts containing 'pillow' but not 'sofa'.
 	 *     @type int          $second                  Second of the minute. Default empty. Accepts numbers 0-60.
 	 *     @type bool         $sentence                Whether to search by phrase. Default false.
 	 *     @type bool         $suppress_filters        Whether to suppress filters. Default false.
@@ -2158,13 +2161,24 @@ class WP_Query {
 		$searchand = '';
 		$q['search_orderby_title'] = array();
 		foreach ( $q['search_terms'] as $term ) {
-			if ( $n ) {
+			// Terms prefixed with '-' should be excluded.
+			$include = '-' !== substr( $term, 0, 1 );
+			if ( $include ) {
+				$like_op  = 'LIKE';
+				$andor_op = 'OR';
+			} else {
+				$like_op  = 'NOT LIKE';
+				$andor_op = 'AND';
+				$term     = substr( $term, 1 );
+			}
+
+			if ( $n && $include ) {
 				$like = '%' . $wpdb->esc_like( $term ) . '%';
 				$q['search_orderby_title'][] = $wpdb->prepare( "$wpdb->posts.post_title LIKE %s", $like );
 			}
 
 			$like = $n . $wpdb->esc_like( $term ) . $n;
-			$search .= $wpdb->prepare( "{$searchand}(($wpdb->posts.post_title LIKE %s) OR ($wpdb->posts.post_content LIKE %s))", $like, $like );
+			$search .= $wpdb->prepare( "{$searchand}(($wpdb->posts.post_title $like_op %s) $andor_op ($wpdb->posts.post_content $like_op %s))", $like, $like );
 			$searchand = ' AND ';
 		}
 
@@ -2264,11 +2278,19 @@ class WP_Query {
 
 		if ( $q['search_terms_count'] > 1 ) {
 			$num_terms = count( $q['search_orderby_title'] );
-			$like = '%' . $wpdb->esc_like( $q['s'] ) . '%';
+
+			// If the search terms contain negative queries, don't bother ordering by sentence matches.
+			$like = '';
+			if ( ! preg_match( '/(?:\s|^)\-/', $q['s'] ) ) {
+				$like = '%' . $wpdb->esc_like( $q['s'] ) . '%';
+			}
 
 			$search_orderby = '(CASE ';
+
 			// sentence match in 'post_title'
-			$search_orderby .= $wpdb->prepare( "WHEN $wpdb->posts.post_title LIKE %s THEN 1 ", $like );
+			if ( $like ) {
+				$search_orderby .= $wpdb->prepare( "WHEN $wpdb->posts.post_title LIKE %s THEN 1 ", $like );
+			}
 
 			// sanity limit, sort as sentence when more than 6 terms
 			// (few searches are longer than 6 terms and most titles are not)
@@ -2281,7 +2303,9 @@ class WP_Query {
 			}
 
 			// sentence match in 'post_content'
-			$search_orderby .= $wpdb->prepare( "WHEN $wpdb->posts.post_content LIKE %s THEN 4 ", $like );
+			if ( $like ) {
+				$search_orderby .= $wpdb->prepare( "WHEN $wpdb->posts.post_content LIKE %s THEN 4 ", $like );
+			}
 			$search_orderby .= 'ELSE 5 END)';
 		} else {
 			// single word or sentence search
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 641098d3b2..cbc209d391 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34933';
+$wp_version = '4.4-alpha-34934';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.