Strange behaviour: json_encode() producing invalid json dependent on input

Question

today I had to deal with some veeeery strange behaviour of php's json_encode(), that I could nowhere read about.

In short:

1. Fetching a row of the database
2. Building a stdClass-object and storing some of the data in there

3. Encoding it using json_encode()

   $obj = new stdClass();
   $obj->a = "foo";
   $obj->b = "bar";
   $obj->c = "doo";
   $obj->d = "baa";
   json_encode( $obj );
   

The Problem:

The returned JSON was buggy: a second (the last one, but only this one!) variable was merged with into the string value of the previous one.

For example it looked like:

{"a": "foo", "b": "bar", "c": "doo', 'd': 'baa"}
                                  ^-------^

Of course I've var_dumped() the object I'm passing over to json_encode()... nothing! Everything was fine and exactly as expected. All the vars were correct and all the values were strings.

But well, that's not enough. Playing around with that, I found out, that changing the order in wich I'm storing the values into the object solved the problem:

$obj->d = "baa";
$obj->c = "doo";

Did not produce an error.

For now I just changed the order of the columns of the database table. But I would like to know, where this never-seen bug comes from and eventually report it.

The bug only appeared on a Debian-VM running PHP 5.3.6. Another VM running PHP 5.3.3 produced correct JSON, just like Mac OS X Lion's integrated webserver running PHP 5.3.8.

My Question

Does anyone experience this problem also?

Greetings from Germany!

The original code

$obj = new stdClass();
$obj->Id = '35';
$obj->EventsCategories_Id = '8';
$obj->Name = 'Blubber';
$obj->OrderValue = '2';
var_dump($obj);
json_encode($obj);

Answer 1

I have no idea about whether this will help or not, but does running the following code produce any different results?

$obj = new stdClass();
$obj->Id = '35';
$obj->EventsCategories_Id = '8';
$obj->Name = 'Blubber';
$obj->OrderValue = '2';

// convert the stdClass object to an array
$obj = (array) $obj;
var_dump($obj);
json_encode($obj);

I think the pertinent question to ask is whether this is:

• an internal PHP issue (possible, but unlikely)
• a problem arising from some environmental issue (a conflicting library?)
• a missing configuration option

While I highly doubt that you've done something wrong (I mean, this is a simple use-case and there's nothing wrong with your code at all), perhaps you could try a couple of other things...

For example, try appending a 2nd argument to the json_encode function:

echo json_encode($obj, JSON_FORCE_OBJECT);

Could you post the results of these two short experiments? This problem is quite strange, indeed. I'm running PHP 5.3.1 and it generates syntactically correct JSON based on your example - no problems to report.