Reply To: Ordering by custom field of relationship field object

• drm10014

• August 28, 2018 at 2:29 am

The posts_join worked. Posting code below in case it helps anyone else.

$args = array(
	'post_type'         => 'artworks',
	'posts_per_page'    => -1,
	'no_found_rows' 	=> true,
	'order'				=> 'ASC',
	'orderby'			=> 'artist_name_artwork_title',
);

add_filter('posts_join', 'test_join', 10, 2 );
function test_join($joins, $wp_query) {
	if ( $wp_query->get( 'orderby' ) != 'artist_name_artwork_title' ) {
		return $joins;
	}	
	global $wpdb;        
	$joins .= "  LEFT JOIN $wpdb->postmeta name ON name.post_id=$wpdb->posts.ID AND name.meta_key='artists_name'" ;
	$joins .= "  LEFT JOIN $wpdb->postmeta lastname ON lastname.post_id=name.meta_value AND lastname.meta_key='artist_last_name'";
	$joins .= "  LEFT JOIN $wpdb->postmeta firstname ON firstname.post_id=name.meta_value AND firstname.meta_key='artist_first_name'";
	return $joins;
}

add_filter('posts_orderby', 'orderby_artist_name_artwork_title', 10, 2);
function orderby_artist_name_artwork_title($orderby_statement, $wp_query) {
	if ( $wp_query->get( 'orderby' ) != 'artist_name_artwork_title' ) {
		return $orderby_statement;
	}	
	global $wpdb;        
	$orderby_statement = "lastname.meta_value, firstname.meta_value, $wpdb->posts.post_title";
	return $orderby_statement;
}

$wp_query = new WP_Query( $args );
		
remove_filter('posts_join', 'test_join', 10 );
remove_filter('posts_orderby', 'orderby_artist_name_artwork_title', 10 );