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<?php
	/**
	* Extend WordPress search to include custom fields
	*
	* http://adambalee.com
	*/

	/**
	* Join posts and postmeta tables
	*
	* http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_join
	*/
	function cf_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', 'cf_search_join' );

	/**
	* Modify the search query with posts_where
	*
	* http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_where
	*/
	function cf_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', 'cf_search_where' );

	/**
	* Prevent duplicates
	*
	* http://codex.wordpress.org/Plugin_API/Filter_Reference/posts_distinct
	*/
	function cf_search_distinct( $where ) {
		global $wpdb;
		
		if ( is_search() ) {
			return "DISTINCT";
		}
		
		return $where;
	}
	add_filter( 'posts_distinct', 'cf_search_distinct' );
?>