Php wordpress在post-meta中更新数组

我在更新post meta中的数组时遇到问题。数组不断覆盖，而不是输入新值

add_action('wp_ajax_update_item_received', 'update_item_received');

function update_item_received() {
$date = date('Y/m/d H:i'); 
$order_id = $_POST['order_id'];
$item_id = $_POST['item_id'];
$received_array = get_post_meta($order_id,"received_array");

if(is_array($received_array[0])) {
    //merge new with old

    $received_array_2[$item_id] = $date;
    array_merge($received_array[0],$received_array_2);
    update_post_meta($order_id,"received_array",$received_array);

} else {

    $received_array = array("$item_id"=>"$date");
    add_post_meta($order_id,"received_array",$received_array);

}

我使用

array\u merge

但新数组与旧数组合并。它变成了一个多维数组

如何求解？

函数默认情况下将post meta作为数组返回。如果您知道始终只有一个，请使用第三个参数

true

，这意味着它将只返回一个元项

然后，您可以添加以下内容：

function update_item_received() {
  $date = date('Y/m/d H:i'); 
  $order_id = $_POST['order_id'];
  $item_id = $_POST['item_id'];
  $received_array = get_post_meta($order_id, "received_array", true);

  if(is_array($received_array)) {
      $received_array[$item_id] = $date;
      update_post_meta($order_id, "received_array", $received_array);
  } else {
      $received_array = array("$item_id"=>"$date");
      add_post_meta($order_id, "received_array", $received_array);
  }
}