Going to try my best to explain this...
In my app I have the need to display the validation errors on a form when the user loads the form initially. In short, they've entered data and saved it, but now the data has been checked and we've detect errors they need to correct before they can fully submit the form. (It's multi step form that can be filled out over multiple sessions...think big.)
Previously I was doing something like:
THIS DOESN'T WORK IN SYMFONY >=2.8.10 See this answer
$entity // passed in as param on action method
$form = $this->createForm(..., $entity);
$csrfToken = 'random_string'; // retrieved from FormConfigInterface
// perform the submit but don't clear missing
$form->submit(['_token' => $csrfToken], false);
This was working, but seems to have broken in Symfony 2.8.10+, but works in 2.8.9. In 2.8.10+ there are no validation errors (the form is considered valid).
I'm able to retrieve the validation errors in a ConstraintViolationListInterface, but I can't find a way to "merge" that with the form (which I think would be the prefered way). Since I couldn't, I tried the above which "fake" submits the form...which seems like a bad idea.
Is there a better/proper way?
(Note: the form is much more complicated and includes validation groups...but I'm not concerned about that or the error in 2.8.10+ at this point.)
