JSON element returning NULL

Question

I am new to JSON and having a problem with checking at getting the error message when there is an error. My code works fine when the result is not an error, so I do somewhat understand what I am doing.
This is the error JSON that I am trying to parse:

{
   "error": {
      "message": "Unsupported get request.",
      "type": "GraphMethodException",
      "code": 100
   }
}

Here is my code that fails:

$jsonurl = "http://graph.facebook.com/JubilationDanceMinistry";
//valid $jsonurl = "http://graph.facebook.com/WhitworthACM";
$json = file_get_contents($jsonurl,0,null,null);
$json_output = json_decode($json);

var_dump($json_output);
// This returns NULL


if (property_exists($json_output->error)) {
        echo "<p>error: $json_output->error->{'message'} </p>";
    } else {
        echo "<p>no error :(</p>";
}

$facebook_id = $json_output->{'id'};
$facebook_name = $json_output->{'name'};
$facebook_link = $json_output->{'link'};

I'm not quite sure. I am a novice with JSON. This was just code I found to parse JSON from a URL and it works with the valid URL. Would you advise me to change it to something else? — michaellindahl
– michaellindahl, Commented Nov 17, 2012 at 5:47

xdazz · Accepted Answer · 2012-11-17 05:45:28Z

1

Because the url returns the 400 Bad Request.

By default, you can't use file_get_contents function to get the response content when the http status code is 400.

You need to set ignore_errors options to true.

$opts = array(
  'http'=>array(
    'ignore_errors' => true
  )
);
$context = stream_context_create($opts);
$jsonurl = "http://graph.facebook.com/JubilationDanceMinistry";
$json = file_get_contents($jsonurl, false, $context);
var_dump($json);

edited Nov 17, 2012 at 5:45

answered Nov 17, 2012 at 5:39

xdazz

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6 Comments

michaellindahl Over a year ago

It is not an invalid URL however. It is related to facebook.com/JubilationDanceMinistry (error is based on privacy) You can visit graph.facebook.com/JubilationDanceMinistry

xdazz Over a year ago

@michaellindahl Ok, no matter the url is, the problem is the http response status, you need to get the error message, right?

michaellindahl Over a year ago

Not exactly. There is no http error as there is going to always be a JSON object. I want to get the "Unsupported get request." from the JSON at graph.facebook.com/JubilationDanceMinistry. I want if in the JSON the element error is present, echo the message.

xdazz Over a year ago

@michaellindahl Have you tried my code? It gives what you want.

xdazz Over a year ago

@michaellindahl The status code is set by the server side of facebook, facebook just think the way you call the url is a bad request. It's nothing related of processing the JSON, you need to get the json content first before you decode it.

|

user229044 · Accepted Answer · 2012-11-17 05:37:30Z

0

You can't chain multiple ->'s with string interpolation.

You'll have resort to passing multiple arguments to echo or to string concatenation:

    echo "<p>error: ", $json_output->error->{'message'}, " </p>";

answered Nov 17, 2012 at 5:37

user229044♦

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1 Comment

michaellindahl Over a year ago

The error happens before the code even reaches this point. The error happens before line 5 when it returns NULL. However, is this code better:

$json_error = $json_output->error; 	$json_message = $json_error->message; 	echo "<p>JSON message: ".$json_message.'</p>';

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