Enable taxonomy wildcard name searching within WordPress search.

functions.php

<?php


/**
 * Callback for WordPress 'pre_get_posts' action.
 * 
 * If doing a search, set the post type to 'post'.
 * 
 * @author Ryan Meier http://www.rfmeier.net/
 * 
 * @param WP_Query $query The current WP_Query object.
 * @return none
 */
function custom_pre_get_posts( $query ){

	if( $query->is_search() && $query->is_main_query() ){
		
		$query->set( 'post_type', 'post' );

	}

}
add_action( 'pre_get_posts', 'custom_pre_get_posts' );


/**
 * Callback for WordPress 'posts_search' filter.
 * 
 * Prevent post title and post content from being searched 
 * if the current post type is 'post'.
 * 
 * @author Ryan Meier http://www.rfmeier.net/
 * 
 * @param string $search The posts search string
 * @param WP_Query $query The current WP_Query object
 * @return string $search The posts search string
 */
function custom_posts_search( $search, $query ){

	if( 'post' == $query->get( 'post_type' ) && is_search() && is_main_query() ){
		return '';
	}

	return $search;
	
}
add_filter( 'posts_search', 'custom_posts_search', 10, 2 );


/**
 * Callback for WordPress 'posts_join' filter.
 * 
 * Join term tables to a WordPress search if the specified post 
 * type is 'post'.
 * 
 * @author Ryan Meier http://www.rfmeier.net/
 * 
 * @param string $join The current where clause JOIN string.
 * @param WP_Query $query The current WP_Query object.
 * @return string $join The current where clause JOIN string.
 */
function posts_join_taxonomies( $join, $query ){

	global $wpdb;
	
	if( 'post' == $query->get( 'post_type' ) && is_search() && is_main_query() ){

		$join .= "
		INNER JOIN
		  {$wpdb->term_relationships} ON {$wpdb->posts}.ID = {$wpdb->term_relationships}.object_id
		INNER JOIN
		  {$wpdb->term_taxonomy} ON {$wpdb->term_taxonomy}.term_taxonomy_id = {$wpdb->term_relationships}.term_taxonomy_id
		INNER JOIN
		  {$wpdb->terms} ON {$wpdb->terms}.term_id = {$wpdb->term_taxonomy}.term_id ";

	}

	return $join;

}
add_filter( 'posts_join', 'posts_join_taxonomies', 10, 2 );


/**
 * Callback for WordPress 'posts_where' filter.
 * 
 * Specify wildcard search on taxonomy names if taxonomy is 
 * within 'post_tag' or 'category'.
 * 
 * @author Ryan Meier http://www.rfmeier.net/
 * 
 * @param String $where The where in the clause
 * @param WP_Query $query The current WP_Query object
 * @return String $where The where in the clause
 */
function tax_search_where( $where, $query ){

  	global $wpdb;

  	if( 'post' == $query->get( 'post_type' ) && is_search() && is_main_query() ){

		$where .= " AND (
		{$wpdb->term_taxonomy}.taxonomy IN('category', 'post_tag') 
		AND
		{$wpdb->terms}.name LIKE ('%".$wpdb->escape( get_query_var('s') )."%') ) ";

  	}
  
  	return $where;

}
add_filter( 'posts_where', 'tax_search_where', 10, 2 );


/**
 * Callback for WordPress 'posts_groupby' filter.
 * 
 * Specify the groupby of the sql clause if doing a search 
 * and post type is 'post'.
 * 
 * @author Ryan Meier http://www.rfmeier.net/
 * 
 * @param String $groupby The groupby within the sql clause.
 * @param WP_Query $query The current WP_Query object.
 * @return String $groupby The groupby within the sql clause.
 */
function tax_search_groupby( $groupby, $query ){

	global $wpdb;

	if( 'post' == $query->get( 'post_type' ) && is_search() && is_main_query() ){

		$groupby = "{$wpdb->posts}.ID";

	}
	
	return $groupby;

}
add_filter( 'posts_groupby', 'tax_search_groupby', 10, 2 );

Hey, I found this, and it was just what i needed for a project. Although, maybe it's better to call is_search() and is_main_query() from the $query object, instead of the global function.

Anyhow, thanks.

Thank you, you are the best

Great thanks 👍