[WordPress] Filter custom post type by multiple admin columns

<?php

add_action( 'restrict_manage_posts', 'mxbd_filter_listings_by_smth' );

function mxbd_filter_listings_by_smth() {
	if (isset($_GET['post_type']) && 'listing' == $_GET['post_type']) {

		$selected_cat = isset($_GET['listing_cat']) ? $_GET['listing_cat'] : '';

		wp_dropdown_categories(array(
			'show_option_all' => __('All Categories', 'mxbd'),
			'taxonomy'        => 'listing_cat',
			'name'            => 'listing_cat',
			'orderby'         => 'name',
			'selected'        => $selected_cat,
			'show_count'      => true,
			'hide_empty'      => false,
			'value_field' => 'slug',
			// 'hierarchical' => 1,
		));
		
		$selected_user = isset($_GET['u_name']) ? $_GET['u_name'] : '';

		wp_dropdown_users( array(
			'show_option_all' => __('All Authors', 'mxbd'),
			'name'            => 'u_name',
			'selected'        => $selected_user,
		));

	}
}

add_filter( 'parse_query', 'mxbd_modify_query_to_filter_by_smth' );
// (wp_query object) $query

function mxbd_modify_query_to_filter_by_smth( $query ) {
	global $pagenow;
	if ( isset($_GET['post_type']) 
		&& 'listing' == $_GET['post_type'] 
		&& is_admin() 
		&& $pagenow == 'edit.php') {

		if(isset($_GET['u_name']) && $_GET['u_name'] != '') {
			$query->query_vars['author'] = $_GET['u_name'];
		}

		if(isset($_GET['u_name']) && $_GET['listing_cat'] != '') {
			$query->query_vars['listing_cat'] = $_GET['listing_cat'];
		}
	}
}