Question

我试图在每个users元素的末尾添加一个新的键值对：

<?php
$json = '[
  {
    "date": "2014-10-09T17:38:19Z",
    "users": [
      {
        "name": "Peter",
        "age": 20
      },
      {
        "name": "Anne",
        "age": 25
      },
      {
        "name": "William",
        "age": 30
      }
    ]
  }
]';

addData ( $json );
function addData($json) {
    $obj = json_decode ( $json, true );
    foreach ( $obj as $items ) {
        foreach ( $items ['users'] as $users ) {
            $array = array (
                    "myKey" => "myValue" 
            );
            array_push ( $users, $array );
        }
    }
    $json = json_encode ( $obj );

    echo $json;
}
?>

所以新json应该是

[  
   {  
      "date":"2014-10-09T17:38:19Z",
      "users":[  
         {  
            "name":"Peter",
            "age":20,
            "myKey":"myValue"
         },
         {  
            "name":"Anne",
            "age":25,
            "myKey":"myValue"
         },
         {  
            "name":"William",
            "age":30,
            "myKey":"myValue"
         }
      ]
   }
]

相反，我将旧的json作为输出，没有新的键值对。

Answer 1

摘自手册关于{{3}}：

为了能够直接修改循环内的数组元素使用＆amp;前面的$ value。在这种情况下，值将由参考

这样您就可以修改$items和$users数组中的值。

我认为你可以这样做：

addData ( $json );
function addData($json) {
    $obj = json_decode ( $json, true );
    foreach ( $obj as &$items ) {
        foreach ( $items ['users'] as &$users ) {
            $users["mykey"] = "myValue";
        }
    }
    $json = json_encode ( $obj );
    echo $json;
}

将导致：

[{
    "date": "2014-10-09T17:38:19Z",
    "users": [{
        "name": "Peter",
        "age": 20,
        "mykey": "myValue"
    }, {
        "name": "Anne",
        "age": 25,
        "mykey": "myValue"
    }, {
        "name": "William",
        "age": 30,
        "mykey": "myValue"
    }]
}]

Answer 2

你的主要问题是foreach提供的数组副本不是实际的数组，因此当你修改$ users时你不会像你想象的那样修改$ json变量。尝试以下内容，我已更改变量名称等以提高可读性

<?php
$json = '[
  {
    "date": "2014-10-09T17:38:19Z",
    "users": [
      {
        "name": "Peter",
        "age": 20
      },
      {
        "name": "Anne",
        "age": 25
      },
      {
        "name": "William",
        "age": 30
      }
    ]
  }
]';

$updated = addData ( $json );
echo $updated;

function addData($json) {
    $ArrList = json_decode ( $json, true );

    foreach ( $ArrList['users'] as $userKey => $user ) {
            $array = array (
                    "myKey" => "myValue" 
             );
        $ArrList['users'][$userKey][] =  $array;
    }

    $json = json_encode ( $ArrList );

    return $json;
}
?>

上面的代码循环遍历结构中的users数组，并在foreach循环中保持键。然后，当我们有结构时，我们希望更新原始数组。

Answer 3

您应该通过引用传递$items和$users数组，如下所示：


function addData($json) {

    $obj = json_decode ( $json, true );

    foreach ( $obj as &$items ) {
        foreach ( $items ['users'] as &$users ) {
            $users['myKey'] = 'myValue';
        }
    }
    $json = json_encode ( $obj );

    echo $json;
}

为什么键值对不会被添加？

3 个答案: