PHP8: media_library: Argument #1 ($value) must be of type Countable

How did you trigger this error?

Can you provide a stack trace or steps to reproduce, starting from installing core

Thanks

Also, some specs regarding your environment etc

I had this error also but it was due to a configuration error on my part. I have a media type that has an additional "Cover image" field. This field had a misconfiguration in the form display mode: it was set to display the preview image using the image style "thumbnail" which I suspect is the default, but this image style does not exist in my project.

When I added a new media entity using the media library "Add media" dialog and uploaded a cover image, the AJAX call would fail inside template_preprocess_image_style() in this part of the code:

$style = ImageStyle::load($variables['style_name']); // Returns NULL, style doesn't exist.
// ...
$style->transformDimensions($dimensions, $variables['uri']); // Error: Call to a member function transformDimensions() on null

This would cause the AJAX request to return a 500 error, so the file widget was not replaced and the file ID was not set in the form. When then the media library file upload form was submitted using either the "Save and select" or "Save and insert" buttons, then the error mentioned in the issue summary was thrown since $values['fids'] would not be populated.

In my case the solution was to configure the form display of my media correctly. This made the error go away.

Still, it could be good to fix this, since the code path obviously has a deficiency:

    // Here if 'upload' is empty we initialize $values to an empty array.
    $values = $form_state->getValue('upload', []);
    // On the very next line we assume that $values['fids'] exists and is countable, but this is clearly not always true.
    if (count($values['fids']) > $element['#cardinality'] && $element['#cardinality'] !== FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED) {
      // ...
    }

So I am marking this as RTBC. Having this fixed is already valuable since it will not lead developers on the wrong path to solving the actual problem they are having (like mine I described above).

Since this is exceedingly minor and will not occur during normal use I think this is fine without having a dedicated test. If it is really needed to test this we can perhaps write a simple unit test that passes in a mocked form state with an empty 'upload' value, rather than simulating a failed AJAX request.

it was set to display the preview image using the image style "thumbnail" which I suspect is the default, but this image style does not exist in my project.

This seems like it might be a core bug in itself - do we need to remove the hardcoding of 'thumbnail' or add some kind of fallback logic for when it's not there?

Created followup to address the hardcoding of the thumbnail image style: #3263700: ImageWidget defaults to the "thumbnail" preview image style but this might not exist. It looks like we can best default to an empty string if the image style doesn't exist. This will set the preview image style to "No preview".

I think we should do #3263700: ImageWidget defaults to the "thumbnail" preview image style but this might not exist first - this might end up repairing old configuration that would fix the bug in #6.

Run into the same on D 9.4.9. Thumbnail exists. The patch fixes it for me. Full backtrace found in dblog:

TypeError: count(): Argument #1 ($value) must be of type Countable|array, null given in count() (line 211 of /var/www/html/web/core/modules/media_library/src/Form/FileUploadForm.php)
#0 /var/www/html/web/core/modules/media_library/src/Form/FileUploadForm.php(211): count(NULL)
#1 [internal function]: Drupal\media_library\Form\FileUploadForm->validateUploadElement(Array, Object(Drupal\Core\Form\FormState), Array)
#2 /var/www/html/web/core/lib/Drupal/Core/Form/FormBuilder.php(1007): call_user_func_array(Array, Array)
#3 /var/www/html/web/core/lib/Drupal/Core/Form/FormBuilder.php(1070): Drupal\Core\Form\FormBuilder->doBuildForm('media_library_a...', Array, Object(Drupal\Core\Form\FormState))
#4 /var/www/html/web/core/lib/Drupal/Core/Form/FormBuilder.php(1070): Drupal\Core\Form\FormBuilder->doBuildForm('media_library_a...', Array, Object(Drupal\Core\Form\FormState))
#5 /var/www/html/web/core/lib/Drupal/Core/Form/FormBuilder.php(574): Drupal\Core\Form\FormBuilder->doBuildForm('media_library_a...', Array, Object(Drupal\Core\Form\FormState))
#6 /var/www/html/web/core/lib/Drupal/Core/Form/FormBuilder.php(320): Drupal\Core\Form\FormBuilder->processForm('media_library_a...', Array, Object(Drupal\Core\Form\FormState))
#7 /var/www/html/web/core/modules/media_library/src/MediaLibraryUiBuilder.php(313): Drupal\Core\Form\FormBuilder->buildForm('Drupal\\dropzone...', Object(Drupal\Core\Form\FormState))
#8 /var/www/html/web/core/modules/media_library/src/MediaLibraryUiBuilder.php(160): Drupal\media_library\MediaLibraryUiBuilder->buildMediaTypeAddForm(Object(Drupal\media_library\MediaLibraryState))
#9 /var/www/html/web/core/modules/media_library/src/MediaLibraryUiBuilder.php(126): Drupal\media_library\MediaLibraryUiBuilder->buildLibraryContent(Object(Drupal\media_library\MediaLibraryState))
#10 /var/www/html/web/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php(824): Drupal\media_library\MediaLibraryUiBuilder->buildUi(Object(Drupal\media_library\MediaLibraryState))
#11 [internal function]: Drupal\media_library\Plugin\Field\FieldWidget\MediaLibraryWidget::openMediaLibrary(Array, Object(Drupal\Core\Form\FormState), Object(Symfony\Component\HttpFoundation\Request))
#12 /var/www/html/web/core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php(69): call_user_func_array(Array, Array)
#13 /var/www/html/web/core/lib/Drupal/Core/Form/EventSubscriber/FormAjaxSubscriber.php(109): Drupal\Core\Form\FormAjaxResponseBuilder->buildResponse(Object(Symfony\Component\HttpFoundation\Request), Array, Object(Drupal\Core\Form\FormState), Array)
#14 [internal function]: Drupal\Core\Form\EventSubscriber\FormAjaxSubscriber->onException(Object(Symfony\Component\HttpKernel\Event\ExceptionEvent), 'kernel.exceptio...', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher))
#15 /var/www/html/web/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(142): call_user_func(Array, Object(Symfony\Component\HttpKernel\Event\ExceptionEvent), 'kernel.exceptio...', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher))
#16 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(229): Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object(Symfony\Component\HttpKernel\Event\ExceptionEvent), 'kernel.exceptio...')
#17 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(92): Symfony\Component\HttpKernel\HttpKernel->handleThrowable(Object(Drupal\Core\Form\FormAjaxException), Object(Symfony\Component\HttpFoundation\Request), 1)
#18 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/Session.php(58): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#21 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#22 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#23 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#24 /var/www/html/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#25 /var/www/html/web/core/lib/Drupal/Core/DrupalKernel.php(709): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#26 /var/www/html/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#27 {main}
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Same issue here now with PHP 8.1

This message already pops up for me when opening the modal with the file upload widget on top and the media selection table below. At that point no file has been uploaded.

So it looks to me, as if the patch was needed or the code has to be adjusted?

It might be related to the other issue in some cases, but doesn't have to, I guess.

See screenshot below: