question about php decode JSON

I still have some question about php decode JSON. the JSON return like this.

all({"Total":30,"Debug":null,"Documents":[
{
  "DocTitle":"Image: A municipal police officer takes positio",
  "Docmultimedia":[
        {
          "DocExpire":"2/7/2011 1:39:02 PM"
        }
      ]
    }
 ...]
});

this is my php code:

foreach ($data->Documents as $result) { 
    echo htmlspecialchars($result->DocTitle).'<br />';
    if(!empty($result->Docmultimedia)){
        echo htmlspecialchars($result->Docmultimedia->DocExpire).'<br />';
    }
}

It return Warning: Invalid argument supplied for foreach(). and echo htmlspecialchars($result->Docmu开发者_开发百科ltimedia->DocExpire), is it write right? Thanks all.

Precondition: The question is based on an MSNBC api (http://api.msnbc.msn.com/documents/GetDocuments?keyword=usa&jsonp=all)

Answer:
API Call
You should call the API without the trailing &jsonp=all, this will make the json evaluateable

API Result MSN returns some values with NaN, NaN is no valid JSON as JSONLint proved.

Result Digesting
I provide a working example on GIST for digesting.

Docmultimedia is an array, as indicated by "Docmultimedia": [ { ... } ] you have to call $result->Docmultimedia[0]->DocExpire to retrieve it. alternatively iterate over it.

I noticed that in the APIs result no Docmultimedia occurs ever, instead DocExpire is an property of the document. Retrieve it via $result->DocExpire.

First, what you are receiving is JSONP, not pure JSON. In order to decode the JSON, you have to remove, all(...); first:

$data = trim($json, 'all();');

Second, you need to decode JSON. PHP does not do this automatically:

$data = json_decode($data);

Now you should be abel to do:

foreach($data->Documents as $result) {
    // something
}

DEMO