I have the same problem with form collections, and commenting the pointed line does stop it from happening for me too.

+1

Same problem here

If anyone is having this issue and can't wait for a fix, here's a temporary one with an intermediate class.

Create this file somewhere:

<?php
// src\Form\MyCollectionType.php

namespace App\Form;

use Symfony\Component\Form\Extension\Core\Type\CollectionType;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\Form\FormView;

/**
 * TODO: Remove this class when issue #37024 is fixed.
 *
 * @see https://github.com/symfony/symfony/issues/37024
 */
class MyCollectionType extends CollectionType
{
    public function finishView(FormView $view, FormInterface $form, array $options)
    {
        trigger_deprecation('', '', "Don't forget to remove the class MyCollectionType");
        if ($form->getConfig()->hasAttribute('prototype') && $view->vars['prototype']->vars['multipart']) {
            $view->vars['multipart'] = true;
        }
    }
}

Now you can use it instead of CollectionType.

It basically overrides the finishView method to how it was before #36088.
Since it's a temporary fix I've added a deprecation, so you'll be reminded to change it later.

I can confirm this issue, and I'm trying to find the original cause to solve it.

I don't think #36088 is the root problem, but might be related to the fact there is no form theme defined for this new block prefix collection_entry and how the right block name is resolved when it does not exist (from afar).

Temporarily, I solved it by adding this theme to my project:

{%- block collection_entry_widget -%}
    {{ form_widget(form) }}
{%- endblock -%}

Yes, the block prefixes hierarchy was incorrect, the new collection_entry block prefix should be placed before all specific ones.

It should be fixed in #37276

Hi @yceruto
I still have the same issue Symfony on v5.2.10 and your temporary fix (setting the collection_entry_widget block) does work for me. The fix from #37276 didn't solve my issue. I am pretty sure it is because I am extending the CollectionType:

class SortableCollectionType extends AbstractType
{
    public function buildView(FormView $view, FormInterface $form, array $options)
    {
        $view->vars['sortable'] = $options['sortable'];
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'sortable' => false,
        ]);
    }

    public function getBlockPrefix()
    {
        return 'sortable_collection';
    }

    public function getParent()
    {
        return CollectionType::class;
    }
}

Any Idea how this could be fixed?

Hi @toooni, could you please create/share a small app reproducing your issue? thanks!

Hi. I still have this problem after migration to Symfony 5.4 from 4.4.
I have deep internal elements of the form including collections with collections.

A simple of the structure:

• form
  • group1 ...
  • group2 ...
  • group3
    • custom element 3 with two collections of custom elements
      • custom collection 1 ...
      • custom collection 2
        • element 1
        • element 2
        • ...
        • collectionType with custom type of 'entry_type' - it causes the exception

I've changed an initial value in extended class of Symfony\Component\Form\Extension\Core\Type\CollectionType::finishView() to fix the bug locally.

use Symfony\Component\Form\Extension\Core\Type\CollectionType as SymfonyCollectionType;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\Form\FormView;

class CollectionType extends SymfonyCollectionType
{

    public function finishView(FormView $view, FormInterface $form, array $options)
    {
        $prefixOffset = -5; // $prefixOffset = -2;

        // next original code
    }
}

It solves the issue only when the value -5 or less (-6, -7, etc).

@dmitrach Please open a new issue and provide a small example application that allows to reproduce your issue.