public function beforeValidate()
    {
        if ($this->owner->{$this->attribute} instanceof UploadedFile) {
            $this->file = $this->owner->{$this->attribute};
            return;
        }

        $this->file = UploadedFile::getInstance($this->owner, $this->attribute);

        if (empty($this->file)) {
            $this->file = UploadedFile::getInstanceByName($this->attribute);
        }

        if ($this->file instanceof UploadedFile) {
            $this->owner->{$this->attribute} = $this->file;
        }
    }