How to echo json object without being wrapped in quotes?

First time dealing with json. I have a php file that processes the post vars sent to it via ajax and then it will echo back a json_encoded array. I cannot iterate thru it because it's wrapped in double quotes. How I do get around this?

The jquery code:

$j.ajax({
   type: 'GET',
   url: 'http://example.com/doaction.php',
   data: 'num=' + fileNum[1],
   success: function(jsonobj) {
     for (var key in jsonobj) {
       if (jsonobj.hasOwnProperty(key)) {
         var jsonob = jsonobj[key];
         console.log(key + " = " + jsonob);
       }
     }
   }
});

The php code in doaction.php:

if ($_GET['num']) {
    $meta = file_meta($_GET['num']); // returns an array
    echo json_encode($me开发者_如何学Cta);
}

file_meta function:

function file_meta($num = 1) {
$num = '_' . $num;
$meta = array(
    'filename' . $num => array(
        'value' => ''),
    'link' . $num => array(
        'value' => ''),
    'description_' . $num => array(
        'value' => ''),
    'metadata' => array(
        'type' => 'checkbox',
        'label' => 'Indicate applicable competencies:',
        'items' => array(
            'core_teaching' . $num => array(
                'label' => 'Core Teaching',
                'value' => 0
            ),
            'teaching_learning' . $num => array(
                'label' => 'Teaching Learning',
                'value' => 0
            ), 
            'instructional_design' . $num => array(
                'label' => 'Instructional Design',
                'value' => 0
            ), 
            'assignment_and_evaluation' . $num => array(
                'label' => 'Assignment & Evaluation',
                'value' => 0
            ),
            'research' . $num => array(
                'label' => 'Research',
                'value' => 0
            ),
            'mentoring' . $num => array(
                'label' => 'Mentoring',
                'value' => 0
            )   
        )
    )
);

return $meta;

}

The result in the console isn't what I was expecting. It should be in key-value pairs but it's gibberish instead like shown below.

 500 = ,
 501 = "
 502 = v
 503 = a
 .
 .
 .

I am pretty sure it's because the json object $.ajax() is getting is wrapped in quotes. When I assign the object without quotes directly to jsonobj I get the correct result. When I call file_meta() directly from within the $.ajax() function I get the correct result:

var jsonobj = <?php $etc = file_meta(); echo json_encode($etc); ?>;
// iterate here...

However that's not what I want because file_meta() needs to be passed with a value from an element retrieved on click event. And sending it via $_GET is the only I know.

Use json_decode() to convert the JSON string into a PHP variable

$var = json_decode('{"file":{"test": 0}}');

In javascript use:

var decoded = eval('{"file":{"test": 0}}');

If you are using the jQuery library use:

var json = '{"file":{"test": 0}}';
var decoded = $.parseJSON(json);