framework/rest/Serializer.php
protected function serializeModelErrors($model)
    {
        $this->response->setStatusCode(422, 'Data Validation Failed.');
        $result = [];
        foreach ($model->getFirstErrors() as $name => $message) {
            $result[] = [
                'field' => $name,
                'message' => $message,
            ];
        }

        return $result;
    }
protected function serializeModelErrors($model)
    {
        $this->response->setStatusCode(422, 'Data Validation Failed.');
        $result = [];
        foreach ($model->getFirstErrors() as $name => $message) {
            $result[] = [
                'field' => $name,
                'message' => $message,
            ];
        }

        return $result;
    }
Serializes the validation errors in a model.
@param Model $model
@return array the array representation of the errors