File form state value is invalid when #multiple is FALSE

The last submitted patch, 4: 3352632-file-form-state-value-4.diff, failed testing. View results →

Seems reasonable, just need to work through the failures

Test patch #4 by following steps:

1. Login as a user who has permission to access Interface translation import page('/admin/config/regional/translate/import').
2. Upload a translation file (.po) via that form.
3. After submitting that form. An error said

Exception: Serialization of 'Symfony\Component\HttpFoundation\File\UploadedFile' is not allowed in serialize() (line 157 of core/lib/Drupal/Core/Batch/BatchStorage.php).

.

Test environment:

• Drupal core version: 9.5.7
• PHP version: 8.1.14

If we change line 97 at /core/lib/Drupal/Core/Render/Element/File.php

from

return is_array($uploaded_file) ? $uploaded_file : [$uploaded_file];

to

return is_array($uploaded_file) ? $uploaded_file : [(array) $uploaded_file];

All tests on my local is passed.

Here is the new patch.

+++ b/core/lib/Drupal/Core/Render/Element/File.php
@@ -91,9 +91,9 @@ public static function valueCallback(&$element, $input, FormStateInterface $form
+      return is_array($uploaded_file) ? $uploaded_file : [(array) $uploaded_file];

this is an array of arrays, is that correct?

Can we add to the existing test coverage for this case?

See \Drupal\Tests\file\Kernel\ManagedFileTest

There is a typo in patch #11.

New patch.

Appreciate the tests @Mingsong and finding where the proposed patch breaks things during serializations, the issue is that calls like this:

// Should ideally return an array of UploadedFile instances.
$files = $form_state->getValue('file');

Should ideally still return an array of \Symfony\Component\HttpFoundation\File\UploadedFile instances, having it being casted to an array makes it harder to retrieve the original value from the form state.

Unless we document that uploaded files should never be read from the $form_state but instead directly from the request (as core seems to handle it in most of its code).

Or potentially introduce a new serializable class to wrap \Symfony\Component\HttpFoundation\File\UploadedFile and use that inside the form state (so that it can work in batch contexts).

Yes, I realized what @Mikey pointed too.

The problem is bigger than I thought. More works need to do.

This also affects Drupal 10 too.