I have a JSON object stored in a mongoDB collection. The object represents the positions of 5 x images, 5 y images, and a tictactoe board image.

On an interval, I send a request to a php file that responds with this object, and then I want to parse that object and move the pieces accordingly.

this is my request:

$.getJSON
(
    "e4.php",
    "",
    function(data)
    {
        world = JSON.parse(data);
        moveObjects(world);
    }
);

but I get: JSON.parse: unexpected character

When I console.log data firebug gives me the right object so I know it's returning properly.

In e4.php:

$criteria = array("name" => "world");

$doc = $collection->findOne($criteria);

$conn->close();

print $doc['world'];

where conn is the connection, and collection is the collection I'm working in.

The database is updated in e3.php:

$encodedworld = $_REQUEST['data'];

$criteria = array("name" => "world");

$doc = $collection->findOne($criteria);

$doc['world'] = $encodedworld;

$collection->save($doc);

$conn->close();

print $encodedworld;

Any ideas? I'm stumped

Thanks in advance.

I have a JSON object stored in a mongoDB collection. The object represents the positions of 5 x images, 5 y images, and a tictactoe board image.

On an interval, I send a request to a php file that responds with this object, and then I want to parse that object and move the pieces accordingly.

this is my request:

$.getJSON
(
    "e4.php",
    "",
    function(data)
    {
        world = JSON.parse(data);
        moveObjects(world);
    }
);

but I get: JSON.parse: unexpected character

When I console.log data firebug gives me the right object so I know it's returning properly.

In e4.php:

$criteria = array("name" => "world");

$doc = $collection->findOne($criteria);

$conn->close();

print $doc['world'];

where conn is the connection, and collection is the collection I'm working in.

The database is updated in e3.php:

$encodedworld = $_REQUEST['data'];

$criteria = array("name" => "world");

$doc = $collection->findOne($criteria);

$doc['world'] = $encodedworld;

$collection->save($doc);

$conn->close();

print $encodedworld;

Any ideas? I'm stumped

Thanks in advance.

• javascript
• jquery
• ajax
• json
• mongodb

• Hard to tell if you don't show the JSON. How are you generating it? – Ruan Mendes Commented Mar 26, 2013 at 22:05
• Edited, although it appears the problem was actually in the original code that I posted. – Cruncher Commented Mar 26, 2013 at 22:13

1 Answer 1

jQuery's getJSON deserializes the JSON for you, so data will be an object graph, not a string. From the documentation:

The success callback is passed the returned data, which is typically a JavaScript object or array as defined by the JSON structure and parsed using the $.parseJSON() method.

So since data has already been deserialized, you don't want or need to call JSON.parse on it. Doing so will implicitly call toString on data, which will return either [object Object] or [object Array], hence JSON.parse not liking it as input. :-) Just use data directly:

$.getJSON
(
    "e4.php",
    "",
    function(world)         // <=== Changed name of argument
    {
        moveObjects(world); // <=== Used it directly
    }
);

Separately: Unless you declared world somewhere you didn't show, your code was also falling prey to The Horror of Implicit Globals. You probably wanted to have var in there. But with the change above, you don't need the variable at all, so...