WooCommerce Admin Custom Products Filtering

woocommerce-products-filter.php

<?php
/**
 * Return (render :-D) HTML Select > Option for filtering
 *
 * @param string $post_type
 * @return void
 */
function webona_custom_product_filters(string $post_type): void
{
	if ($post_type !== 'product') {
		return;
	}

	$options = [
		'with-images' => __('Produkty s obrázky', 'webona'),
		'no-images' => __('Produkty bez obrázků', 'webona'),
	];

	$selected = isset($_GET['webona_custom_product_filter']) ? $_GET['webona_custom_product_filter'] : null;

	$o = '';

	$o .= '<select name="webona_custom_product_filter">';
	$o .= '    <option value>Zobrazit vše</option>';

	foreach ($options as $value => $option) {
		$is_selected = ($value === $selected) ? 'selected="selected"' : '';
		$o .= '    <option value="' . $value . '" ' . $is_selected . '>' . $option . '</option>';
	}

	$o .= '</select>';

	echo $o;
}

add_action('restrict_manage_posts', 'webona_custom_product_filters');


/**
 * Applying filter, if exists
 *
 * @param WP_Query $query
 * @return void
 */
function apply_webona_custom_product_filters(\WP_Query $query): void
{
	global $pagenow;

	if (
		$query->is_admin &&
		($pagenow == 'edit.php') &&
		isset($_GET['webona_custom_product_filter']) &&
		($_GET['webona_custom_product_filter'] !== '') &&
		($_GET['post_type'] == 'product')
	) {

		$filter = $_GET['webona_custom_product_filter'];

		switch ($filter) {
			case 'no-images':
				$meta_key_query = array(
					array(
						'key' => '_thumbnail_id',
						'compare' => 'NOT EXISTS',
					)
				);
				$query->set('meta_query', $meta_key_query);
				break;

			case 'with-images':
				$meta_key_query = array(
					array(
						'key' => '_thumbnail_id',
						'compare' => 'EXISTS',
					)
				);
				$query->set('meta_query', $meta_key_query);
				break;

			default:
				break;
		}

	}

	return;
}

add_action('pre_get_posts', 'apply_webona_custom_product_filters');