Latest release notes

docs/topics/3.0-announcement.md

@@ -560,6 +560,35 @@ The following usage will *now raise an error*:
 
     email = serializers.EmailField(source='email')
 
+#### The `UniqueValidator` and `UniqueTogetherValidator` classes.
+
+REST framework now provides two new validators that allow you to ensure field uniqueness, while still using a completely explicit `Serializer` class instead of using `ModelSerializer`.
+
+The `UniqueValidator` should be applied to a serializer field, and takes a single `queryset` argument.
+
+    from rest_framework import serializers
+    from rest_framework.validators import UniqueValidator
+
+    class OrganizationSerializer(serializers.Serializer):
+        url = serializers.HyperlinkedIdentityField(view_name='organisation_detail')
+        created = serializers.DateTimeField(read_only=True)
+        name = serializers.CharField(
+            max_length=100,
+            validators=UniqueValidator(queryset=Organisation.objects.all())
+        )
+
+The `UniqueTogetherValidator` should be applied to a serializer, and takes a `queryset` argument and a `fields` argument which should be a list or tuple of field names.
+
+    class RaceResultSerializer(serializers.Serializer):
+        category = serializers.ChoiceField(['5k', '10k'])
+        position = serializers.IntegerField()
+        name = serializers.CharField(max_length=100)
+
+        default_validators = [UniqueTogetherValidator(
+            queryset=RaceResult.objects.all(),
+            fields=('category', 'position')
+        )]
+
 ## Generic views
 
 #### Simplification of view logic.
@@ -633,6 +662,16 @@ The `COMPACT_JSON` setting has been added, and can be used to revert this behavi
         'COMPACT_JSON': False
     }
 
+#### File fields as URLs
+
+The `FileField` and `ImageField` classes are now represented as URLs by default. You should ensure you set Django's standard `MEDIA_URL` setting appropriately.
+
+You can revert this behavior, and display filenames as the representation, using the `UPLOADED_FILES_USE_URL` settings key:
+
+    REST_FRAMEWORK = {
+        'UPLOADED_FILES_USE_URL': False
+    }
+
 #### Throttle headers using `Retry-After`.
 
 The custom `X-Throttle-Wait-Second` header has now been dropped in favor of the standard `Retry-After` header. You can revert this behavior if needed by writing a custom exception handler for your application.