PHP JSON 获取键和值

Question

我有以下 JSON 格式：

{
    "S01": ["001.cbf", "002.cbf", "003.cbf", "004.cbf", "005.cbf", "006.cbf", "007.cbf", "008.cbf", "009.cbf"],
    "S02": ["001.sda", "002.sda", "003.sda"],
    "S03": ["001.klm", "002.klm"]
}

我尝试使用此代码：

$json = json_decode('{"S01":["001.cbf","002.cbf","003.cbf","004.cbf","005.cbf","006.cbf","007.cbf","008.cbf","009.cbf"],"S02":["001.sda","002.sda","003.sda"],"S03":["001.klm","002.klm"]}');

foreach($json as $key => $val) {
     if ($key) { echo 'KEY IS: '.$key; };
     if ($val) { echo 'VALUE IS: '.$value; };
     echo '<br>';
}

但是我得到了空结果...我需要得到这样的输出：

KEY IS: S01
VALUE IS: 001.cbf
VALUE IS: 002.cbf
VALUE IS: 003.cbf
VALUE IS: 004.cbf
VALUE IS: 005.cbf
VALUE IS: 006.cbf
VALUE IS: 007.cbf
VALUE IS: 008.cbf
VALUE IS: 009.cbf

KEY IS: S02
VALUE IS: 001.sda
VALUE IS: 002.sda
VALUE IS: 003.sda

KEY IS: S03
VALUE IS: 001.klm
VALUE IS: 002.klm

这是我需要的，以便我可以使用值和键名生成 ul 和 li 元素...这是存储在 mysql 数据库中的 JSON 格式，并被读取到需要解析上述输出中的 JSON 的 php 脚本中，所以我可以使用输出创建 ul 和 li 元素。

我尝试执行 foreach 但结果为空？我知道当我得到价值时，我需要使用explode(', ', $value) 进行爆炸字符串，但我无法在 PHP 中根据需要读取 $value 和 $key。

Answer 1

这解决了您的问题，您必须将 $json 转换为数组，因为它被视为 stdClass 对象；）

<?php 
$json = json_decode('{"S01":["001.cbf","002.cbf","003.cbf","004.cbf","005.cbf","006.cbf","007.cbf","008.cbf","009.cbf"],"S02":["001.sda","002.sda","003.sda"],"S03":["001.klm","002.klm"]}');
foreach($json as $key => $val) {
    echo "KEY IS: $key<br/>";
    foreach(((array)$json)[$key] as $val2) {
        echo "VALUE IS: $val2<br/>";
    }
}
?>

Try It Online!

我建议你下次遇到麻烦时使用函数 var_dump($var)，它会帮助你找出问题所在。

Answer 2

$json = '{"S01":["001.cbf","002.cbf","003.cbf","004.cbf","005.cbf","006.cbf","007.cbf","008.cbf","009.cbf"],"S02":["001.sda","002.sda","003.sda"],"S03":["001.klm","002.klm"]}';

$array = json_decode($json, true);

foreach($array as $key => $val) {
  echo 'KEY IS:'.$key.'<br/>';
  foreach($val as $_key => $_val) {
   echo 'VALUE IS: '.$_val.'<br/>';
  }
}

Answer 3

如果您执行 var_dump($json) 来观察结果，您会看到它看起来像这样...

$json = json_decode('{"S01":["001.cbf","002.cbf","003.cbf","004.cbf","005.cbf","006.cbf","007.cbf","008.cbf","009.cbf"],"S02":["001.sda","002.sda","003.sda"],"S03":["001.klm","002.klm"]}');

var_dump($json);


object(stdClass)[1]
  public 'S01' => 
    array (size=9)
      0 => string '001.cbf' (length=7)
      1 => string '002.cbf' (length=7)
      2 => string '003.cbf' (length=7)
      3 => string '004.cbf' (length=7)
      4 => string '005.cbf' (length=7)
      5 => string '006.cbf' (length=7)
      6 => string '007.cbf' (length=7)
      7 => string '008.cbf' (length=7)
      8 => string '009.cbf' (length=7)
  public 'S02' => 
    array (size=3)
      0 => string '001.sda' (length=7)
      1 => string '002.sda' (length=7)
      2 => string '003.sda' (length=7)
  public 'S03' => 
    array (size=2)
      0 => string '001.klm' (length=7)
      1 => string '002.klm' (length=7)

所以你实际上有一个数组数组。

因此，对于每个“键”，关联的“val”是一个必须循环遍历的数组。

所以你需要遍历每个键，然后遍历每个 val 数组。

foreach ($json as $key => $val) {
    echo 'KEY IS: ' . $key;
    echo '<br>';
    foreach ($val as $value) {
        echo 'VALUE IS: ' . $value;
        echo '<br>';
    }
    echo '<br>';
}

结果输出是...

KEY IS: S01
VALUE IS: 001.cbf
VALUE IS: 002.cbf
VALUE IS: 003.cbf
VALUE IS: 004.cbf
VALUE IS: 005.cbf
VALUE IS: 006.cbf
VALUE IS: 007.cbf
VALUE IS: 008.cbf
VALUE IS: 009.cbf

KEY IS: S02
VALUE IS: 001.sda
VALUE IS: 002.sda
VALUE IS: 003.sda

KEY IS: S03
VALUE IS: 001.klm
VALUE IS: 002.klmlm
VALUE IS: 002.klm