public function invalidate($field, $errors = [])
    {
        $schema = $this->schema();

        if (func_num_args() === 1) {
            foreach ($field as $key => $value) {
                if ($schema->hasRelation($key) && $this->has($key)) {
                    $this->{$key}->invalidate($value);
                } else {
                    $this->invalidate($key, $value);
                }
            }
            return $this;
        }
        if ($errors) {
            $this->_errors[$field] = (array) $errors;
        }
        return $this;
    }