Adds filters to search post meta using default WP search (#393)

functions.php

@@ -151,6 +151,11 @@ function _s_widgets_init() {
  */
 require get_template_directory() . '/inc/acf.php';
 
+/**
+ * Load custom ACF search functionality.
+ */
+require get_template_directory() . '/inc/acf-search.php';
+
 /**
  * Load custom filters and hooks.
  */

inc/acf-search.php

@@ -0,0 +1,70 @@
+<?php
+/**
+ * ACF/Post Meta Search.
+ *
+ * Extend WordPress search to include custom fields.
+ * https://adambalee.com
+ *
+ * @package _s
+ */
+
+/**
+ * Join posts and postmeta tables
+ * http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_join
+ *
+ * @param string $join The SQL query.
+ * @return $join The updated query.
+ * @author Corey Collins
+ */
+function _s_search_join( $join ) {
+	global $wpdb;
+
+	if ( is_search() ) {
+		$join .= ' LEFT JOIN ' . $wpdb->postmeta . ' ON ' . $wpdb->posts . '.ID = ' . $wpdb->postmeta . '.post_id ';
+	}
+
+	return $join;
+}
+add_filter( 'posts_join', '_s_search_join' );
+
+/**
+ * Modify the search query with posts_where.
+ * http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_where
+ *
+ * @param string $where The SQL query.
+ * @return $where The updated query.
+ * @author Corey Collins
+ */
+function _s_search_where( $where ) {
+	global $pagenow, $wpdb;
+
+	if ( is_search() ) {
+		$where = preg_replace(
+			'/\(\s*' . $wpdb->posts . '.post_title\s+LIKE\s*(\'[^\']+\')\s*\)/',
+			'(' . $wpdb->posts . '.post_title LIKE $1) OR (' . $wpdb->postmeta . '.meta_value LIKE $1)',
+			$where
+		);
+	}
+
+	return $where;
+}
+add_filter( 'posts_where', '_s_search_where' );
+
+/**
+ * Prevent duplicates.
+ * http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_distinct
+ *
+ * @param string $where The SQL query.
+ * @return $where The updated query.
+ * @author Corey Collins
+ */
+function _s_search_distinct( $where ) {
+	global $wpdb;
+
+	if ( is_search() ) {
+		return 'DISTINCT';
+	}
+
+	return $where;
+}
+add_filter( 'posts_distinct', '_s_search_distinct' );