# Validating Models ## 驗證數據完整性（Validating Data Integrity） [Phalcon\\Mvc\\Model](http://docs.iphalcon.cn/api/Phalcon_Mvc_Model.html)provides several events to validate data and implement business rules. The special “validation” event allows us to call built-in validators over the record. Phalcon exposes a few built-in validators that can be used at this stage of validation. The following example shows how to use it: ~~~ <?php namespace Store\Toys; use Phalcon\Mvc\Model; use Phalcon\Validation; use Phalcon\Validation\Validator\Uniqueness; use Phalcon\Validation\Validator\InclusionIn; class Robots extends Model { public function validation() { $validator = new Validation(); $validator->add( "type", new InclusionIn( [ "domain" => [ "Mechanical", "Virtual", ] ] ) ); $validator->add( "name", new Uniqueness( [ "message" => "The robot name must be unique", ] ) ); return $this->validate($validator); } } ~~~ The above example performs a validation using the built-in validator “InclusionIn”. It checks the value of the field “type” in a domain list. If the value is not included in the method then the validator will fail and return false. > For more information on validators, see the[Validation documentation](http://docs.iphalcon.cn/reference/validation.html). The idea of creating validators is make them reusable between several models. A validator can also be as simple as: ~~~ <?php namespace Store\Toys; use Phalcon\Mvc\Model; use Phalcon\Mvc\Model\Message; class Robots extends Model { public function validation() { if ($this->type === "Old") { $message = new Message( "Sorry, old robots are not allowed anymore", "type", "MyType" ); $this->appendMessage($message); return false; } return true; } } ~~~ ## 驗證信息（Validation Messages） [Phalcon\\Mvc\\Model](http://docs.iphalcon.cn/api/Phalcon_Mvc_Model.html)has a messaging subsystem that provides a flexible way to output or store the validation messages generated during the insert/update processes. Each message is an instance of[Phalcon\\Mvc\\Model\\Message](http://docs.iphalcon.cn/api/Phalcon_Mvc_Model_Message.html)and the set of messages generated can be retrieved with the`getMessages()`method. Each message provides extended information like the field name that generated the message or the message type: ~~~ <?php if ($robot->save() === false) { $messages = $robot->getMessages(); foreach ($messages as $message) { echo "Message: ", $message->getMessage(); echo "Field: ", $message->getField(); echo "Type: ", $message->getType(); } } ~~~ [Phalcon\\Mvc\\Model](http://docs.iphalcon.cn/api/Phalcon_Mvc_Model.html)can generate the following types of validation messages: | Type | Description | | --- | --- | | PresenceOf | Generated when a field with a non-null attribute on the database is trying to insert/update a null value | | ConstraintViolation | Generated when a field part of a virtual foreign key is trying to insert/update a value that doesn’t exist in the referenced model | | InvalidValue | Generated when a validator failed because of an invalid value | | InvalidCreateAttempt | Produced when a record is attempted to be created but it already exists | | InvalidUpdateAttempt | Produced when a record is attempted to be updated but it doesn’t exist | The`getMessages()`method can be overridden in a model to replace/translate the default messages generated automatically by the ORM: ~~~ <?php namespace Store\Toys; use Phalcon\Mvc\Model; class Robots extends Model { public function getMessages() { $messages = []; foreach (parent::getMessages() as $message) { switch ($message->getType()) { case "InvalidCreateAttempt": $messages[] = "The record cannot be created because it already exists"; break; case "InvalidUpdateAttempt": $messages[] = "The record cannot be updated because it doesn't exist"; break; case "PresenceOf": $messages[] = "The field " . $message->getField() . " is mandatory"; break; } } return $messages; } } ~~~ ## 驗證失敗事件（Validation Failed Events） Another type of events are available when the data validation process finds any inconsistency: | Operation | Name | Explanation | | --- | --- | --- | | Insert or Update | notSaved | Triggered when the INSERT or UPDATE operation fails for any reason | | Insert, Delete or Update | onValidationFails | Triggered when any data manipulation operation fails |