Input file not populated in edit form

[arsrobota]

Hello,
I use Symfony 6.3.12 ang Twig Extra Bundle 3.8.0.
I'm working on a form with Symfony in which users can create a collection of rows, each contains a file upload and a couple fields. Nor collection type or form type is mapped to an entity, I process submitted data by myself back in controller.
Submitting new data works but when I inject persisted data in the form for edition with an existing file (an instance of Symfony\Component\HttpFoundation\File\File containing absolute path to file on the server), the file is not passed to the form field, and this one remains empty with "No file selected" displayed in the template.

Here is my code:
Controller:

$documents = [
	'docs' => \array_map(
		function ($row) use($uploadDir, $base) {
			$a = [
                                 // 'file' is an instance of Symfony\Component\HttpFoundation\File\File
				'file' => new File(\sprintf('%s\%s\%s', $uploadDir, $base, $row->getPathDoc())),
				'idDoc' => $row->getIdDoc(),
				'types' => \explode('|', $row->getPj()),
				'is_fake' => (bool)$row->getFauxDoc()
			];
			return $a;
		},
		$docs        // array of data from DB query
	)
];
$docForm = $this->createForm(JustificatifsCollectionType::class, $documents);

JustificatifCollectionType.php

public function buildForm(FormBuilderInterface $builder, array $options): void
{
	$builder
		->add('docs', CollectionType::class, [
			'label' => false,
			'entry_type' => JustificatifType::class,
			'allow_add' => true,
			'allow_delete' => true,
			'entry_options' => [
				'attr' => [
					'class' => 'd-flex'
				]
			]
		]);
}

JustificatifType.php

public function buildForm(FormBuilderInterface $builder, array $options): void
{
	$builder
		->add('file', FileType::class, [
			'label' => 'Fichier',
		])
		->add('types', ChoiceType::class, [
			'choices' => [
				'Contrat' => 'CT',
				'PI' => 'PI',
				'JD' => 'JD',
				'RIB' => 'RIB',
				'Autre' => 'AUT',
			],
			'expanded' => true,
			'multiple' => true,
			'attr' => [
				'class' => 'd-flex'
			],
		])
		->add('is_fake', CheckboxType::class, [
			'label' => 'Faux document(s)',
			'value' => true,
			'required' => false,
			'attr' => [
				'class' => 'd-flex'
			],
			'label_attr' => [
				'class' => 'form-check-label'
			],
		]);
}

Template

<div class="modal-dialog modal-xl">
	<div class="modal-content">
		{{ form_start(docForm) }}
		<div class="modal-header">
			<h1 class="modal-title fs-5" id="uploadModalLabel">Import de documents</h1>
			<button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Fermer"></button>
		</div>
		<div class="modal-body">
			<div {{ stimulus_controller('form-collection') }}
					data-form-collection-index-value="{{ docForm.docs|length > 0 ? docForm.docs|last.vars.name + 1 : 0 }}"
					data-form-collection-prototype-value="{{ form_widget(docForm.docs.vars.prototype)|e('html_attr') }}">
				<ul {{ stimulus_target('form-collection', 'collectionContainer') }}>
					{% for doc in docForm.docs.children %}
						<li>{{ form_widget(doc) }}</li>
					{% endfor %}
				</ul>
				<button class="btn btn-success float-end"
						type="button" {{ stimulus_action('form-collection', 'addCollectionElement') }}>
					Ajouter
				</button>
			</div>
		</div>
		<div class="modal-footer">
			<button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Fermer</button>
			<button type="submit" class="btn btn-primary start">Valider</button>
		</div>
		{{ form_end(docForm) }}
	</div>
</div>

form-collection.js

import {Controller} from '@hotwired/stimulus'

export default class extends Controller {
    opened = false;

    static targets = [
        'collectionContainer'
    ]

    static values = {
        index: Number,
        prototype: String
    }

    addCollectionElement(event) {
        const item = document.createElement('li');
        item.innerHTML = this.prototypeValue.replace(/__name__/g, this.indexValue);
        this.collectionContainerTarget.appendChild(item);
        this.indexValue++;
    }
}

I cannot figure out what I did wrong.
Does anyone see what is missing ?

Thanks by advance.

EDIT: if I upload another file in the already existing row, this one is not updated but another row is created.

[fabpot]

You should report that to the main Symfony repository, or maybe start a discussion thread there to get some help. Thank you.

[arsrobota]

Hello,
Thanks for replying. I already started a discussion on Symfony repository (no answer, so far) but as I suspect a problem on rendering side I thought this discussion belonged more to Twig repository.

[fabpot]

Twig forms are part of Symfony, not Twig :)

[arsrobota]

I know, but my form is correct. The problem appears when the file input is supposed to be "filled" with data.

[xabbuh]

HTML file input forms cannot be populated with existing data. That’s why you don’t see anything even if you data is bound correctly to your form.

[arsrobota]

Hi Xabbuh, thanks for replying.
That's an interesting point, given that Symfony documentation gives an example of edting form with an file input.
Anyway, I think I will refactor my form to give up any file choice edition possibility.
Thank you for your help.