php - 如何在 PHP 中解码具有多个对象的 JSON 字符串？

Question

在您的帮助下，我知道如何用一个对象解码 JSON 字符串 How to decode a JSON String

但现在我想用几个对象改进解码 JSON 字符串，但我不明白该怎么做。

这是一个例子:

{ "inbox": [
  { "firstName": "Brett", "lastName":"McLaughlin" },
  { "firstName": "Jason", "lastName":"Hunter" },
  { "firstName": "Elliotte", "lastName":"Harold" }
 ],
"sent": [
  { "firstName": "Isaac", "lastName": "Asimov" },
  { "firstName": "Tad", "lastName": "Williams" },
  { "firstName": "Frank", "lastName": "Peretti" }
 ],
"draft": [
  { "firstName": "Eric", "lastName": "Clapton" },
  { "firstName": "Sergei", "lastName": "Rachmaninoff" }
 ]
}

1. 如何只用一个 foreach() 来解码上面的 JSON 字符串？
2. 如何检测对象的名称:收件箱，在这个 foreach() 上发送或草稿？

Answer 1

新答案

关于您修改后的问题:foreach 实际上适用于属性以及多值项(数组)，details here .因此，例如，在您的问题中使用 JSON 字符串:

$data = json_decode($json);
foreach ($data as $name => $value) {
    // This will loop three times:
    //     $name = inbox
    //     $name = sent
    //     $name = draft
    // ...with $value as the value of that property
}

在属性的主循环中，您可以使用内部循环遍历每个属性指向的数组条目。因此，例如，如果您知道每个顶级属性都有一个数组值，并且每个数组条目都有一个“firstName”属性，则此代码:

$data = json_decode($json);
foreach ($data as $name => $value) {
    echo $name . ':'
    foreach ($value as $entry) {
        echo '  ' . $entry->firstName;
    }
}

...将显示:

inbox:  Brett  Jason  Elliottesent:  Issac  Tad  Frankdraft:  Eric  Sergei

Old answer(s)

Begin editRe your comment:

Now I would like to know how to decode JSON string with several objects!

The example you posted does have several objects, they're just all contained within one wrapper object. This is a requirement of JSON; you cannot (for example) do this:

{"name": "I'm the first object"},
{"name": "I'm the second object"}

该 JSON 无效。 必须 有一个顶级对象。它可能只包含一个数组:

{"objects": [
    {"name": "I'm the first object"},
    {"name": "I'm the second object"}
]}

...或者您当然可以为各个对象命名:

{
    "obj0": {"name": "I'm the first object"},
    "obj1": {"name": "I'm the second object"}
}

结束编辑

您的示例是一个包含三个属性的对象，每个属性的值都是一个对象数组。事实上，它与您链接的问题中的示例没有太大区别(它也有一个具有数组值属性的对象)。

所以:

$data = json_decode($json);
foreach ($data->programmers as $programmer) {
    // ...use $programmer for something...
}
foreach ($data->authors as $author) {
    // ...use $author for something...
}
foreach ($data->musicians as $musician) {
    // ...use $musician for something...
}