Render a Checkbox in Twig; Boolean expected error

Question

I'm trying to render a checkbox inside a form but got the next error:

TransformationFailedException in Form.php line 1149: Unable to transform value for property path "[active]": Expected a Boolean.

Yes, what I send is an integer 0 or 1, but twig get them as string and it has sense but I really can't find how to render the checkbox.

This is the controller:

    $form = $form->add('active', 'checkbox', array('label' => 'User active?','required' => false));

And this is the Twig side:

{{ form_widget(form.active, { attr: { 'class': 'form-control' }}) }}

Any idea?

Answer 1

In your form add a model transformer as @Rinat suggested:

$form->add('active', 'checkbox', array('label' => 'User active?','required' => false));
$form->get('active')
     ->addModelTransformer(new CallbackTransformer(
         function ($activeAsString) {
             // transform the string to boolean
             return (bool)(int)$activeAsString;
         },
         function ($activeAsBoolean) {
             // transform the boolean to string
             return (string)(int)$activeAsBoolean;
         }
    ));

More details here: http://symfony.com/doc/current/cookbook/form/data_transformers.html