public function getFormField($form, $fieldClass = null, array $extra = []) { if (!empty($this->types)) { $types = []; foreach ($this->types as $type) { $types[] = FileHelper::getMimeTypeByExtension($type); } $extra = array_merge($extra, ['html' => ['accept' => implode('|', $types)]]); } return parent::getFormField($form, FormFileField::className(), $extra); }