JsonResponse makes it impossible to send literal null

[zachmullen]

The default value of the $data parameter for JsonResponse is null, but when it is set to null, the actual value sent in the response is in fact {}. This is problematic because it makes it impossible to send a literal value of null, which is valid JSON. The distinction is important, because in javascript {} evaluates truthy and null evaluates falsy.

[xabbuh]

This seems to be the desired value since there actually is a test ensuring this behaviour: https://github.com/symfony/symfony/blob/master/src/Symfony/Component/HttpFoundation/Tests/JsonResponseTest.php#L18-22

You can use the setData() method to send a null response:

$response = new JsonResponse();
$response->setData(null);

[zachmullen]

Thanks, that works as a workaround.

[stof]

the goal is that calling new JsonResponse() without data returns a {} response. Given that we cannot have new arrayObject() as default value, we had to make a special handling for null in the constructor.
The fix is indeed to call setData explicitly.

Note that this cannot be changed for BC (I don't know many APIs returning null as JSON content though btw). I'm closing this issue

[lol768]

Can we please document this behaviour somewhere?

It's bizarre behaviour to me, and suggests a misunderstanding of the JSON specification from whoever originally implemented it, but at least if it was written down somewhere in the PHPdoc I wouldn't have wasted time wondering what was going on

[derrabus]

Can we please document this behaviour somewhere?

Go ahead and propose the piece of documentation that would've helped you to https://github.com/symfony/symfony-docs/

[OskarStark]

What's about adding also a testcase for this behavior and using setData ?