在php中检查特定的JSON对象是否可用

I have following JSON:

我有以下JSON:

$p={
  "main1" : [
    {
      "child1" : valueA,
      "child2" : valueB,
      "child3" : valueC,
    },
    {
      "child1" : value1,
      "child3" : value3,
    },
  ],
  "main2" : "valueMain2"
}

The element child2 has to be checked if it exists or not and then the value is taken. I am using json_decode:

必须检查元素child2是否存在,然后获取该值。我正在使用json_decode:

$response = json_decode($p,true);

How do I check if an element exists or not in PHP? Do I have to make separate function or is there built-in functionality?

如何在PHP中检查元素是否存在?我是否必须制作单独的功能或是否有内置功能?

3 个解决方案

#1

The same way you'd check if a key of any array exists:

以同样的方式检查是否存在任何数组的键:

with isset($array['key']) or array_key_exists('key',$array).

with isset($ array ['key'])或array_key_exists('key',$ array)。

#2

Here's how I've been doing it.

这就是我一直在做的事情。

$child2exists = count($response['main1']['child2']);

If ($child2exists == 1) 
{ 
    echo "EXISTS"; 
}
else
{ 
    echo "DOESNT EXIST"; 
}

Hope this helps.

希望这可以帮助。

#3

You can use the json decode as an object and check whatever exist:

您可以使用json decode作为对象并检查存在的内容:

$response = json_decode($p);
if (isset($response->main2)) {
   echo $response->main2; // valueMain2
}

Also you can use a foreach to get the item list:

您还可以使用foreach获取项目列表:

foreach ($response->main1 as $item) {
   echo $item->child1; // valueA value1
}

#1