Woocommerce：按“特價”過濾管理產品

Question

我在下面找到了這段代碼，它在 Woocommerce 管理產品列表上添加了一個不錯的“按銷售過濾”下拉過濾器。

不知何故，此代碼與訂單編輯頁面有沖突。 如果我打開一個編輯訂單會出現錯誤“注意：未定義索引：post_type in /wp-content/plugins/code-snippets/php/snippet-ops.php(469) : eval()'d code on line 36"

第 36 行說： if (!is_admin() || $_GET['post_type'] != "product" || !$selected) {

有沒有辦法修復代碼片段，以免弄亂訂單編輯頁面？

這是我正在使用的完整代碼。

/*
 * Woocommerce Filter by on sale
 */
function custom_woocommerce_filter_by_onsale($output) {
    global $wp_query;
    
    $selected = filter_input(INPUT_GET, 'product_sale', FILTER_VALIDATE_INT);
    if ($selected == false) {
        $selected = 0;
    }
    
    $output .= '
        <select id="dropdown_product_sale" name="product_sale">
            <option value="">Filter by sale</option>
            <option selected="selected" value="1">On sale</option>
            <option selected="selected" value="2">Not on sale</option>
        </select>
    ';
    
    return $output;
}
add_action('woocommerce_product_filters', 'custom_woocommerce_filter_by_onsale');
 
 
 
/*
 * Woocommerce Filter by on sale where statement
 */
function custom_woocommerce_filter_by_onsale_where_statement($where) {
    global $wp_query, $wpdb;
 
    // Get selected value
    $selected = filter_input(INPUT_GET, 'product_sale', FILTER_VALIDATE_INT);
    
    // Only trigger if required
    if (!is_admin() || $_GET['post_type'] != "product" || !$selected) {
        return $where;
    }
 
    $productsIDs = [];
    if ($selected == 1) {
        $querystr = '
            SELECT p.ID, p.post_parent
            FROM ' . $wpdb->posts . ' p
            WHERE p.ID IN (
                SELECT post_id FROM ' . $wpdb->postmeta . ' pm WHERE pm.meta_key = "_sale_price" AND pm.meta_value > \'\'
            )
        ';
        
        $pageposts = $wpdb->get_results($querystr, OBJECT);
        
        $productsIDs = array_map(function($n){
            return $n->post_parent > 0 ? $n->post_parent : $n->ID;
        }, $pageposts);
    } elseif ($selected == 2) {
        $querystr = '
            SELECT p.ID, p.post_parent
            FROM ' . $wpdb->posts . ' p
            WHERE p.ID NOT IN (
                SELECT post_id FROM ' . $wpdb->postmeta . ' pm WHERE pm.meta_key = "_sale_price" AND pm.meta_value > \'\'
            )
        ';
        
        $pageposts = $wpdb->get_results($querystr, OBJECT);
        
        $productsIDs = array_map(function($n){
            return $n->post_parent > 0 ? $n->post_parent : $n->ID;
        }, $pageposts);
    }
    
    $where .= ' AND ' . $wpdb->posts . '.ID IN (' . implode(",", $productsIDs) . ') ';
    
    return $where;
}
add_filter('posts_where' , 'custom_woocommerce_filter_by_onsale_where_statement');

Answer 1

警告是由於 $GET 並不總是可用的事實。

代替：

if (!is_admin() || $_GET['post_type'] != "product" || !$selected) {

用

if (!is_admin() || !isset($_GET['post_type']) || $_GET['post_type'] != "product" || !$selected) {

或更好

if (!is_admin() || get_query_var('post_type') != "product" || !$selected) {