[3.x]: Model Validation for Fileuploads fails when on PHP 8.1

[JensvdHeydt]

What happened?

Description

I'm using a custom controller to receive file uploads. Those uploads are validated via a YII file extension validator. Since upgrading to PHP 8.1 the model validation failed to work and resulted in an error regarding the file extension being forbidden.

I've noticed that when I add the following option 'checkExtensionByMimeType' => false, the validation works again.
This seems to be a known problem with YII. See: yiisoft/yii2#19243

Steps to reproduce

1. Define a File Model using the following code:

class UploadForm extends Model
{
public ?UploadedFile $file;

public function rules(): array
{
    return [
      [['file'], 'file', 'skipOnEmpty' => false, 'extensions' => 'png,jpg,jpeg,svg,pdf,doc,ppt'],
    ];
}

}

2. Validate a model containing (for example) a file named "image.png"

Expected behavior

The validation should work when uploading a file with a valid extension.

Actual behavior

The validation fails with PHP 8.1

Craft CMS version

3.8.13

PHP version

8.1

Operating system and version

linux

Database type and version

mariadb

Image driver and version

No response

Installed plugins and versions

[brandonkelly]

This was fixed in Yii 2.0.47, so we just created a 3.9 branch that updates Yii to 2.0.48.1 (#13444).

To get the update early, change your craftcms/cms requirement to 3.9.x-dev as 3.9.0-alpha in composer.json, and then run composer update.

[JensvdHeydt]

@brandonkelly Thank you very much! I've yet to find time to review the change but I guess update Yii will do the trick, since it's a Yii problem after all.

[brandonkelly]

Craft 3.9.0 was just released with Yii 2.0.48.1 🎉