Yii2 File Validation Not Working After Upload - file-upload

Question

I'm not sure if this is a new bug or what's going on, but I'm having trouble getting the Yii2 validator to recognize a file is there after it's been uploaded. The client side validation works fine.
Rules for the model:
return [
[['store_id', 'name', 'csv'], 'required'],
[['store_id', 'created_at', 'updated_at'], 'integer'],
[['name'], 'string', 'max' => 255],
[['csv'], 'file', 'skipOnEmpty' => false, 'maxSize'=>1024 * 1024 * 2],
];
Controller Action:
public function actionUploadFromCsv()
{
$store = Yii::$app->user->identity->store;
$store_csv = new StoreCsv;
$store_csv->store_id = $store->id;
$store_csv->name = $store_csv->getDefaultName();
if (Yii::$app->request->isPost) {
$store_csv->csv = UploadedFile::getInstance($store_csv, 'csv');
if ($store_csv->upload()) {
return $this->redirect(['view-csv', 'id'=>$store_csv->id]);
}
return json_encode($store_csv->getErrors());
}
return $this->render('csv_upload', [
'store'=>$store,
'csv'=>$store_csv
]);
}
Model Upload() Function:
public function upload()
{
if ($this->validate()) {
$file_name = uniqid(rand(), false) . '.' . $this->csv->extension;
$this->csv->saveAs(Yii::getAlias('#backend') . '/web/store/' . $this->store_id . '/csv/' . $file_name);
$this->csv = $file_name;
return $this->save();
}
return false;
}
Form Markup:
<?php $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]); ?>
<?= $form->field($csv, 'csv')->fileInput() ?>
<div class="form-group">
<?= Html::submitButton('Submit', ['class' => 'btn btn-primary']) ?>
</div>
<?php ActiveForm::end(); ?>
Currently when I perform the upload I get this error after validation fails:
{"csv":["Please upload a file."]}
If I change 'skipOnEmpty' to true, however, it works fine. It saves the model and moves and renames the temporary file. I would like to get validation working though, so I can restrict to certain extensions. What's the deal? I've spent hours trouble shooting this.

Answer 1

I figured out what my problem here is. After saving the file I try to rename it, however, the way I do it here takes away the association of this attribute as a file.
Wrong:
$this->csv = $file_name;
Right:
$this->csv->name = $file_name;
In addition, I originally asked this question because I was having trouble getting the validator to work, restricting extensions. It would not recognize "xls" or "csv" after the client side validation when I did $model->validate(). I just found that this is a known issue due to the MIME TYPE validator:
https://github.com/yiisoft/yii2/issues/6148
The solution to the extension issue is to set checkExtensionByMimeType to false:
[['csv'], 'file', 'skipOnEmpty' => false, 'extensions'=>['xls', 'csv'], 'checkExtensionByMimeType'=>false, 'maxSize'=>1024 * 1024 * 2],

Answer 2

What is your FORM markup? View the page source within the browser. Files are ignored unless the form markup has has multipart/form-data.
<form action="upload.php" method="post" enctype="multipart/form-data">