How to use DTO for CollectionType in symfony?

Question

symfony

Good day everyone. I've run into a problem that I can't figure out.
There is a form, FirstFormType, on the form there is a CollectionType field referring to the second form. For the second form, you need to fill in the values ​​​​through the DataTransformer. Below is a simplified code of two forms. Simplified to use CallbackTransformer`a instead of a full-fledged transformer. The problem is that the fields of the subform from the CollectionType are not filled -(
The first form

<?php

namespace True\AdminBundle\Form\Type;

/* uses */

class FirstFormType extends AbstractType
{
    public function buildForm (FormBuilderInterface $builder, array $options)
    {
        $builder->add('qwe', CollectionType::class, [
            'label' => 'asdasd',
            'required' => false,
            'prototype' => true,
            'allow_add' => true,
            'allow_delete' => true,
            'mapped' => false,
            'entry_type' => SecondCollectionFormType::class,
            'entry_options'  => array(
                /*'fields' => $fields,
                'descriptions' => $options['descriptions'][$key],*/
            ),
        ]);
        $builder->get('qwe')
            ->addModelTransformer(new CallbackTransformer(
                function ($tagsAsArray) {
                    // Проблемное место
                    $result['qwe'][] = ['logo' => '222', 'description' => '123'];
                    return $result;
                },
                function ($tagsAsString) {
                    $result['qwe'][] = ['logo' => '222', 'description' => '123'];
                    return $result;
                }
            ))
        ;
        $builder
            ->add('submit', SubmitType::class, [
                'label' => 'Сохранить',
            ])
        ;
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            'fields' => null,
            'descriptions' => null,
            'em' => null,
            'template' =>  null,
            'sectionName' => null,
            'doctrine' => null,
            'websiteId' => null,
        ));
    }

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

The form that is inserted into the CollectionType

<?php
namespace True\AdminBundle\Form\Type;
/* uses */

class SecondCollectionFormType extends AbstractType
{
    public function buildForm (FormBuilderInterface $builder, array $options)
    {
        $builder->add('logo', TextType::class, [
            'label' => $label,
            'required' => false,
            'mapped' => false,
            ]);
        $builder->add('description', TextareaType::class, [
            'label' => $label,
            'required' => false,
            'mapped' => false,
            ]);
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            'fields' => null,
            'descriptions' => null,
        ));
    }

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

}

Answer 1

So you clearly indicated that the data does not need to be mapped.
Use form events to manually set the data.