检索具有动态关键字字符串的对象变量 - Retrieve object variables with dynamic key strings

Retrieve object variables with dynamic key strings

我有一个名为"required"的属性的PHP对象。此"必需"字段是一个嵌套数组。我想用动态字符串（用于属性名称和数组索引）从这个对象中检索所需的键。我怎样才能做到这一点？

$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[curses][classes][lesson_name_required]

我假设您知道如何正确访问对象/数组，并尝试动态生成所需值的路径。下面的代码将允许您传递一个字符串，并在对象中筛选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);

$desiredKey的值为required[courses][lessons][lesson_name_required]。这不是一个财产。现在$desiredKey只是一个字符串。PHP不会解释字符串以访问数组属性。您还忘记了数组键周围的引号。你可以这样访问你想要的值：

$desiredValue = $myObj->required["courses"]["lessons"]["lesson_name_required"];

替换此：

$desiredKeyArrayPart = "[courses][lessons][lesson_name_required]";
$desiredKeyAttributePart = "required";
$desiredKey = $desiredKeyAttributePart . $desiredKeyArrayPart;
// Get the value (Should return 1)
$desiredValue = $myObj->$desiredKey;

通过这个：

$desiredValue = $myObj->required['courses']['lessons']['lesson_name_required'];

你试图做这件事的方式行不通。此外，最好引用数组值以避免出现警告。