👍 - I have just encountered this issue where I wish to display validation failures from the bound object when the form is initially displayed.

@bwoodmansee Test changes/additions are probably required for this PR to be accepted

👍 - we need this too

👍 Same here.

Hi, thank you for taking the time to submit this PR! How would you validate the form in this case? I.e., before its submission?

Right now I've got code that imitates the ViolationMapper - but it'd be nice to be able to extend or reuse the ValidationListener in a form type that has a special requirement for validation besides POST_SUBMIT.

It isnt possible right now because the ViolationMapper checks specifically for submitted forms.

https://github.com/symfony/symfony/blob/2.8/src/Symfony/Component/Form/Extension/Validator/EventListener/ValidationListener.php#L72

So - if I understand correctly - you want to create a form, validate it, display it and then handle the submission (+ validate again, obviously), right?

Yep, I'd like the initial display of the form to contain validation errors.

Here's how we're validating in this case:

/**
 * @return array
 */
public static function getSubscribedEvents()
{
    return array(FormEvents::POST_SET_DATA => 'postSetData');
}

/**
 * @param FormEvent $event
 */
public function postSetData(FormEvent $event)
{
    $mapper = new ViolationMapper();
    $mapper->setFormSubmissionRequired(false);
    $validationListener = new ValidationListener($this->validator, $mapper);
    $validationListener->validateForm($event);
}

Then dealing with the form errors like normal

+1 for this. Simply said: We have the exact same use-case.

@webmozart What's your final call on this? Should we add this?

@fabpot I think it's useful. I've seen a few projects where this was a problem.

However, we can't add an argument to mapViolation(), since that would break BC as of symfony/symfony-docs#5735.

But the current PR does not add any argument, so looks like it is safe regarding BC breaks.

@fabpot That's true, however as of now the PR is not very useful. This functionality is only useful to have in core if it can be controlled through an option when creating a form. Setting this as a global flag (the violation mapper is registered in the DIC) would create problems with bundles that expect the flag to be set to a specific value.

Given that the violation mapper is a global service, we have to pass the option into mapViolation(). Alternatively, we can add a setter to ViolationMapper, but we can't add that setter to the interface. Also, that setter makes the service stateful and I'd rather avoid that to prevent side effects.

I'd also be interested in this feature being added. We're in the process of upgrading from 2.3 to 2.8 and this has caused us problems.

Our use case, if it helps, is that a (GET) request is submitted to us by a client which contains the parameters to populate a form. In a lot of cases, the form is fully populated and the submission works fine. We make a decision there to ignore the form and to go straight to the next part of our journey. This provides a positive user experience in our case as it's slightly faster.

In other cases however, users have errors in their data. We'd like to therefore show them how they can resolve the errors. Sometimes we have no data, in which case we can just show them an empty form and showing errors is redundant.

However, if they provide, say, 2/3rds of the data, we don't want them to have to manually figure out which ones are submitted and which aren't. We'd like to instead show the errors that they need to resolve.

Because of the isSubmitted check it will never show the errors. Removing the isSubmitted check returns the functionality to how it was before.

@edhgoose looks like #18053 could solve your issue

I don't understand why not just submit null to trigger a first validation before creating the view ?

In case the form has a csrf protection there is still this workaround:

$form = ... // create the form

$form->handleRequest($request);

$view = $form->createView(); // generates the token

if ($form->isSubmitted() && $form->isValid()) {
    // Process it
} else {
    // Force a first validation (you can set empty_data option to have full control here)
    $form->submit(array('_token' => $view->children['_token']->vars['value']));
}

$view = $form->createView(); // has initial errors if any

Closing as @webmozart is right when saying that having a global config is a no-go for such a feature and because #18053 looks like a good alternative.