The validation service implements the `EPiServer.Validation.IValidationService` interface to validate object instances. You can retrieve the service instance from the IOC container. The service has a single method: `IEnumerable<ValidationError> Validate(object instance);`.

The service locates implementations of `EPiServer.Validation.IValidate<T>` during initialization. When a validation request comes for an object instance, the service checks which of the registered validators that are assigned from the passed-in object, and those validators are then called to perform validation.

## IValidate<T> interface

To implement a validator, create a class that implements the `EPiServer.Validation.IValidate<T>` interface, which has a single method defined as: `IEnumerable<ValidationError> Validate(T instance);`.

You do not need an explicit registration. The validation service locates classes, that implement the interface, during initialization. When you call `EPiServer.Validation.IValidationService` to validate an object instance, it calls each validator to which you can assign the object instance. You can implement a validator for an interface or a base class, and then calls that validator whenever you validate an object that implements/inherits the registered type.

## IContentSaveValidate<TContent> 

To implement a validator that only runs when content is being saved you can implement `IContentSaveValidation`, this interface extends `IValidate` but also adds contextual information such as which save action that was used.

## DataAnnotationsValidator

Use the `EPiServer.Validation.DataAnnotationsValidator<T>` base class when you implement a validator that validates against attributes that inherit `System.ComponentModel.DataAnnotations.ValidationAttribute`.

## Content validation

`EPiServer.IContentRepository.Save` validates a content instance before it is saved to verify that required properties are set. It also validates the properties on the model class (the class inheriting `PageData` or `BlockData` or that implements `IContent`) against any attributes inheriting from `System.ComponentModel.DataAnnotations.ValidationAttribute`.

You can prevent validation by using the save action `EPiServer.DataAccess.SaveAction.SkipValidation` flag during save as follows (here it assumes that an instance of `EPiServer.IContentRepository` has been retrieved from IOC container and assigned to variable `contentRepository`): `contentRepository.Save(page, SaveAction.Publish | SaveAction.SkipValidation);`