php - 在 PHP 中将二维数组转换为 JSON

Question

我的目标是使单个数据库命中以生成一个对象的 JSON 数组，该数组具有的属性也可以是对象数组，也可以具有任意(但已知)深度的对象数组等属性。

我使用 PDO 对象从数据库中获取二维数组。

$stmt = $this->pdo->prepare($sql);
$stmt->execute($args);
$TwoDimArray = $stmt->fetchAll(PDO::FETCH_ASSOC);
return $TwoDimArray;

所以在我的例子中，我有一个测验，它可以有问题，也可以有答案。所以深度为 3。假设我有一个二维数组，如下表所示，我将如何使用该数据制作这个 JSON 数组。 (注意:为清楚起见，已删除其他数据，但问题和答案可能具有其他属性。)

编辑:这是我的尝试。对于一般情况，它效率低得可怕，而且不是很抽象，但这段代码将为小数据集提供正确的答案。

$data = ($database -> query($sql,$args)); // the result is $TwoDimArray
$quizes = array();
$quiz_id_list = array();
foreach($data as $quizkey => $quizvalue){
    if(!in_array($quizvalue["quiz_id"], $quiz_id_list)) {
        array_push($quiz_id_list, $quizvalue["quiz_id"]);
        $question_id_list = array();
        $questions = array();
        foreach ($data as $questionskey => $questionsvalue) {
            if ($quizvalue["quiz_id"] == $questionsvalue["quiz_id"] && !in_array($questionsvalue["question_id"], $question_id_list)) {
                $answers = array();
                array_push($question_id_list, $questionsvalue["question_id"]);
                foreach ($data as $answerskey => $answersvalue) {
                    $myanswer = array();
                    if ($questionsvalue["question_id"] == $answersvalue["question_id"]) {
                        $myanswer["answer_id"] = $answersvalue["answer_id"];
                        array_push($answers, $myanswer);

                    }
                }
                $myquestion = array();
                $myquestion["question_id"] = $questionsvalue["question_id"];
                $myquestion["answers"] = $answers;
                array_push($questions, $myquestion);

            }
        }
        $myquiz = array();
        $myquiz["quiz_id"] = $quizvalue["quiz_id"];
        $myquiz["questions"] = $questions;
        array_push($quizes, $myquiz);
    }

}
return json_encode($quizes);

$data 的内容如下所示:

array (
  0 =>array('quiz_id' => '1',   'question_id' => '1', 'answer_id' => '1',),
  1 =>array('quiz_id' => '1',   'question_id' => '1', 'answer_id' => '2',),
  ...
  5 =>array('quiz_id' => '1', 'question_id' => '2', 'answer_id' => '6',),
  6 =>array('quiz_id' => '1', 'question_id' => '2', 'answer_id' => '7',),
  ...
  22 =>array('quiz_id' => '2', 'question_id' => '6', 'answer_id' => '23',),
  23 =>array('quiz_id' => '2', 'question_id' => '6', 'answer_id' => '24',),
)

结果应该返回一个如下所示的 json 对象:

[
    {
        "quiz_id": 1,
        "questions": [
            {"question_id":1, "answers": [{"answer_id":1}, {"answer_id":2}, {"answer_id":3},{"answer_id":4}]}, 
            {"question_id":2, "answers": [{"answer_id":5}, {"answer_id":6}, {"answer_id":7},{"answer_id":8}]}, 
            {"question_id":3, "answers": [{"answer_id":9}, {"answer_id":10}, {"answer_id":11},{"answer_id":12}]}
        ]
    },
    {
        "quiz_id": 2,
        "questions": [
            {"question_id":4, "answers": [{"answer_id":13}, {"answer_id":14}, {"answer_id":15},{"answer_id":16}]}, 
            {"question_id":5, "answers": [{"answer_id":17}, {"answer_id":18}, {"answer_id":19},{"answer_id":20}]}, 
            {"question_id":6, "answers": [{"answer_id":21}, {"answer_id":22}, {"answer_id":23},{"answer_id":24}]}
        ]
    }
]

Answer 1

你说这是 $TwoDimArray 的内容 没有什么可以用它做的。我怀疑还缺少一些东西。

array ( 'quiz_id' => '1', 'question_id' => '1', 'answer_id' => '1', ), 
array ( 'quiz_id' => '1', 'question_id' => '1', 'answer_id' => '2', ), 
array ( 'quiz_id' => '1', 'question_id' => '1', 'answer_id' => '3', ),

这将摆脱你的“冗余数据”:

foreach($TwoDimArray as $value){
  $quiz[$value['quiz_id']][$value['question_id']][$value['question_id']] =  1;
}