php - 使用动态键字符串检索对象变量

Question

我有一个 PHP 对象，其属性名为“required”。这个“必填”字段是一个嵌套数组。我想使用动态字符串(用于属性名称和数组索引)从此对象中检索所需的键。我怎样才能实现这一目标？

$myObj = new StdClass;
$myObj->required = array(
        "name_required" => 1,
        "courses" => array(
                "course_name_required" => 1,
                "lessons_required" => 1,
                "lessons" => array(
                        "lesson_name_required" => 1,
                        "lesson_file_required" => 1,
                        "is_viewed_required" => 1,
                    ),
            ),

);
// Desired Key I want to retrieve using dynamic strings.
$desiredKeyArrayPart = "[courses][lessons][lesson_name_required]";
$desiredKeyAttributePart = "required";
$desiredKey = $desiredKeyAttributePart . $desiredKeyArrayPart;

// Get the value (Should return 1)
$desiredValue = $myObj->$desiredKey;

我希望返回值 1，但这会引发运行时错误: PHP 注意:未定义的属性:stdClass::$required[courses][lessons][lesson_name_required]

Answer 1

我假设您知道如何正确访问对象/数组，并且正在尝试动态生成所需值的路径。以下代码将允许您传递一个字符串，并通过一个对象过滤该字符串中的多个键。

<?php
$myObj = new StdClass;
$myObj->required = array(
  "name_required" => 1,
  "courses" => array(
    "course_name_required" => 1,
    "lessons_required" => 1,
    "lessons" => array(
      "lesson_name_required" => 1,
      "lesson_file_required" => 1,
      "is_viewed_required" => 1,
    ),
  ),
);
// Desired Key I want to retrieve using dynamic strings.
$desiredKeyArrayPart = "[courses][lessons][lesson_name_required]";
$desiredKeyAttributePart = "required";

// Set our searchObject to $myObj->required using Variable Variables
$searchObject = $myObj->$desiredKeyAttributePart;
// Match all of the keys in our string
preg_match_all('/\[(.*?)\]/', $desiredKeyArrayPart, $keyMap);
// Foreach key that we found
foreach ($keyMap[1] as $key) {
  // Change our $searchObject to the new key's value
  $searchObject = $searchObject[$key];
}
// We found our object
var_dump($searchObject);