frontend\modules\user\models\UserMeta::rules PHP Method

    public function rules()
    {
        return [[['user_id'], 'required'], [['user_id', 'target_id', 'created_at'], 'integer'], [['type', 'target_type'], 'string', 'max' => 100], [['value'], 'string', 'max' => 255]];
    }