          serializer.save(user=request.user)  # Include the user when saving.
  
  #### Using `serializers.ValidationError`.
  
  Previously `serializers.ValidationError` error was simply a synonym for `django.core.exceptions.ValidationError`. This has now been altered so that it inherits from the standard `APIException` base class.
  
 
</s> remove **TODO: Needs documenting.**
 </s> add REST framework also now includes explicit validator classes for validating the `unique_for_date`, `unique_for_month`, and `unique_for_year` model field constraints. These are used internally instead of calling into `Model.full_clean()`.

These classes are documented in the [Validators](../api-guide/validators.md) section of the documentation. </s> remove Significant new functionality continues to be planned for the 3.1 and 3.2 releases. These releases will present simple upgrades, without the same level of fundamental API changes necessary for the 3.0 release.
 </s> add Significant new functionality continues to be planned for the 3.1 and 3.2 releases. These releases will correspond to the two [Kickstarter stretch goals](https://www.kickstarter.com/projects/tomchristie/django-rest-framework-3) - "Feature improvements" and "Admin interface". Further 3.x releases will present simple upgrades, without the same level of fundamental API changes necessary for the 3.0 release.
#### Using `.is_valid(raise_exception=True)`

The `.is_valid()` method now takes an optional boolean flag, `raise_exception`.

Calling `.is_valid(raise_exception=True)` will cause a `ValidationError` to be raised if the serializer data contains validation errors. This error will be handled by REST framework's default exception handler, allowing you to remove error response handling from your view code.

The handling and formatting of error responses may be altered globally by using the `EXCEPTION_HANDLER` settings key.

This change also means it's now possible to alter the style of error responses used by the built-in generic views, without having to include mixin classes or other overrides.

          serializer.save(user=request.user)  # Include the user when saving.
  
#### Using `.is_valid(raise_exception=True)`

The `.is_valid()` method now takes an optional boolean flag, `raise_exception`.

Calling `.is_valid(raise_exception=True)` will cause a `ValidationError` to be raised if the serializer data contains validation errors. This error will be handled by REST framework's default exception handler, allowing you to remove error response handling from your view code.

The handling and formatting of error responses may be altered globally by using the `EXCEPTION_HANDLER` settings key.

This change also means it's now possible to alter the style of error responses used by the built-in generic views, without having to include mixin classes or other overrides.

  #### Using `serializers.ValidationError`.
  
  Previously `serializers.ValidationError` error was simply a synonym for `django.core.exceptions.ValidationError`. This has now been altered so that it inherits from the standard `APIException` base class.
  
keep add keep keep keep keep
 Fill in TODOs for 3.0 beta release notes 
docs/topics/3.0-announcement.md