JSON到PHP数组得到“试图获取非对象的属性”错误

Question

您好，我有这样的 Json：

[{
    "exam_code": "1",
    "name": "Name1",
    "surname": "Surname1",
    "father_name": "Fname1",
    "id_number": "211111",
    "district_number": "21",
    "school_number": "025",
    "gender": "F",
    "variant": "A",
    "grade": "4",
    "sector": "A",
    "foreign_language": "I",
    "answerList": {
        "gradeFour": {
            "lesson1": ["A", "C", "C", "C", "A", "A", "B", "B", " ", "C", "C", "B", "A", "C", "C", "B", "B", "C", "B", "A"],
            "lesson2": ["B", "A", " ", "C", " ", "B", " ", "B", "B", "C", " ", " ", "B", "A", "A", "A", "C", "A", "B", "B"],
            "lesson3": ["A", "C", "B", "B", "A", "A", "C", "A", "C", "C"],
            "lesson4": ["B", "B", "A", "B", "B"],
            "lesson5": ["B", "A", "A", "B", "B"],
            "lesson6": ["B", "A", "A", "B", "A", "B", "A", "A", "C", "B"]
        }
    }
}]

我正在尝试在 foreach 循环中打印课程答案。

尝试以下代码：

<?php
$msc = microtime(true);


$array = (json_decode($raw_str,true));

foreach($array as $value){
echo $value['id_number'];
    echo '<br/>';

   foreach($value -> answerList->gradeFour as $val){
        echo $val;    
  }

  echo '<br>---------------------------';
  echo '<br>';

}
$msc = microtime(true)-$msc;
echo ($msc * 1000) . ' ms'; // in millseconds
?>

但出现此错误

注意：试图获取非对象的属性 G:\xampp\htdocs\siec\string_test.php on line 50 注意：试图得到 在线 G:\xampp\htdocs\siec\string_test.php 中非对象的属性 50 警告：为 foreach() 提供的参数无效 G:\xampp\htdocs\siec\string_test.php 在第 50 行

Answer 1

在您的第二个 foreach 循环中，$value 是一个数组。所以你必须用括号[]而不是->：

foreach($value['answerList']['gradeFour'] as $val) {

Answer 2

你的代码有两个问题：

• 首先，您必须使用括号而不是 ->

• 其次，您需要使用嵌套循环（两个 fors）来打印成绩，因为您有多个课程（另一个数组）的多个成绩（一个数组）。

所以你的完整代码会是这样的：

$msc = microtime(true);

$array = (json_decode($raw_str,true));

foreach($array as $value){
echo $value['id_number'];
    echo '<br/>';

   foreach($value['answerList']['gradeFour'] as $course){
        foreach($course as $val){
            echo $val;    
        }   
    }

  echo '<br>---------------------------';
  echo '<br>';

}

Answer 3

你的问题在第 5 行 您必须将其解码为关联数组 阅读json_decode

查看下面的代码，它会帮助你更了解

 $array = json_decode($raw_str);

 foreach($array as $value){
    echo $value->id_number;
    echo '<br/>';

    foreach($value->answerList->gradeFour as $key => $val){
       echo $key;
       echo "<pre>";
       print_r($val);
       echo "</pre>";

    }

    echo '<br>---------------------------';
    echo '<br>';

}