Twig with Symfony 2 displaying json encoded variables different between prod and dev

Question

We're building a Symfony 2 application that sends some data from controller to view:

Controller

$user = array(
    'configuration' => array(
        'levels' => array(
            'warning' => 0.05,
            'danger'  => 0.10,
        ),
    ),
);

return $this->render(
    'MyWebsiteBundle:Core:searchResults.html.twig',
    array(
        'userJSON'  => json_encode($user)
    )
);

View

<script language="javascript">
    user = $.parseJSON("{{ userJSON }}");
</script>

Result

On dev the result looks like this and works as expected:

user = $.parseJSON("\x7B\x22configuration\x22\x3A\x7B\x22levels\x22\x3A\x7B\x22warning\x22\x3A0.05,\x22danger\x22\x3A0.1\x7D\x7D\x7D");

On the other hand, on prod the result is encoded in a different manner, thus displaying errors in console:

user = $.parseJSON("{"configuration":{"levels":{"warning":0.05,"danger":0.1}}}");

Console Error: Uncaught SyntaxError: Unexpected token &

What generates this difference?

Solution 1

Edit: Also check @Lulhum's solution below. Up-vote it if it's better so I will select it as the correct answer.

The "problem" was Twig autoescaping variables. I used Twig's raw filter to skip autoescaping like this:

<script language="javascript">
    user = $.parseJSON('{{ userJSON | raw }}');
</script>

Now it prints:

user = $.parseJSON('{"configuration":{"levels":{"warning":0.05,"danger":0.1}}}');

Links: Symfony 2 Docs - Output escaping

Solution 2

It is better to avoid using the raw filter when possible. You can here achieve the same behavior with the escape filter (doc).

<script language="javascript">
    user = $.parseJSON('{{ userJSON | escape('js') }}');
</script>

Comments

[Kvn91]

gosh you just saved my life ! was trying 1000 solutions and in fact I just replaced "raw" by "escape('js')" and it worked fine ! Thx

[Vincent Decaux]

Same for me ! even if the printed string is impossible to read for human, works like a charm