jnlsn

add_filter('posts_clauses', 'posts_clauses_with_tax', 10, 2);
function posts_clauses_with_tax( $clauses, $wp_query ) {
	global $wpdb;
	//array of sortable taxonomies
	$taxonomies = array('example-taxonomy', 'other-taxonomy');
	if (isset($wp_query->query['orderby']) && in_array($wp_query->query['orderby'], $taxonomies)) {
		$clauses['join'] .= "
			LEFT OUTER JOIN {$wpdb->term_relationships} AS rel2 ON {$wpdb->posts}.ID = rel2.object_id
			LEFT OUTER JOIN {$wpdb->term_taxonomy} AS tax2 ON rel2.term_taxonomy_id = tax2.term_taxonomy_id
			LEFT OUTER JOIN {$wpdb->terms} USING (term_id)

luetkemj

// This gist is now maintained on github at https://github.com/luetkemj/wp-query-ref

<?php
/**
* WordPress Query Comprehensive Reference
* Compiled by luetkemj - luetkemj.github.io
*
* CODEX: http://codex.wordpress.org/Class_Reference/WP_Query#Parameters
* Source: https://core.trac.wordpress.org/browser/tags/4.9.4/src/wp-includes/query.php
*/

mjangda

<?php

/**
 * Remove a given term from the specified post
 *
 * Helper function since this functionality doesn't exist in core
 */
function my_remove_post_term( $post_id, $term, $taxonomy ) {

	if ( ! is_numeric( $term ) ) {