UniqueTogetherValidator

rest_framework/serializers.py

@@ -23,6 +23,7 @@ from rest_framework.utils.field_mapping import (
     get_relation_kwargs, get_nested_relation_kwargs,
     ClassLookupDict
 )
+from rest_framework.validators import UniqueTogetherValidator
 import copy
 import inspect
 
@@ -95,7 +96,7 @@ class BaseSerializer(Field):
     def is_valid(self, raise_exception=False):
         if not hasattr(self, '_validated_data'):
             try:
-                self._validated_data = self.to_internal_value(self._initial_data)
+                self._validated_data = self.run_validation(self._initial_data)
             except ValidationError as exc:
                 self._validated_data = {}
                 self._errors = exc.message_dict
@@ -223,15 +224,43 @@ class Serializer(BaseSerializer):
             return html.parse_html_dict(dictionary, prefix=self.field_name)
         return dictionary.get(self.field_name, empty)
 
-    def to_internal_value(self, data):
+    def run_validation(self, data=empty):
         """
-        Dict of native values <- Dict of primitive datatypes.
+        We override the default `run_validation`, because the validation
+        performed by validators and the `.validate()` method should
+        be coerced into an error dictionary with a 'non_fields_error' key.
         """
+        if data is empty:
+            if getattr(self.root, 'partial', False):
+                raise SkipField()
+            if self.required:
+                self.fail('required')
+            return self.get_default()
+
+        if data is None:
+            if not self.allow_null:
+                self.fail('null')
+            return None
+
         if not isinstance(data, dict):
             raise ValidationError({
                 api_settings.NON_FIELD_ERRORS_KEY: ['Invalid data']
             })
 
+        value = self.to_internal_value(data)
+        try:
+            self.run_validators(value)
+            self.validate(value)
+        except ValidationError as exc:
+            raise ValidationError({
+                api_settings.NON_FIELD_ERRORS_KEY: exc.messages
+            })
+        return value
+
+    def to_internal_value(self, data):
+        """
+        Dict of native values <- Dict of primitive datatypes.
+        """
         ret = {}
         errors = {}
         fields = [field for field in self.fields.values() if not field.read_only]
@@ -253,12 +282,7 @@ class Serializer(BaseSerializer):
         if errors:
             raise ValidationError(errors)
 
-        try:
-            return self.validate(ret)
-        except ValidationError as exc:
-            raise ValidationError({
-                api_settings.NON_FIELD_ERRORS_KEY: exc.messages
-            })
+        return ret
 
     def to_representation(self, instance):
         """
@@ -355,6 +379,14 @@ class ModelSerializer(Serializer):
     })
     _related_class = PrimaryKeyRelatedField
 
+    def __init__(self, *args, **kwargs):
+        super(ModelSerializer, self).__init__(*args, **kwargs)
+        if 'validators' not in kwargs:
+            validators = self.get_unique_together_validators()
+            if validators:
+                self.validators.extend(validators)
+                self._kwargs['validators'] = validators
+
     def create(self, attrs):
         ModelClass = self.Meta.model
 
@@ -381,6 +413,36 @@ class ModelSerializer(Serializer):
             setattr(obj, attr, value)
         obj.save()
 
+    def get_unique_together_validators(self):
+        field_names = set([
+            field.source for field in self.fields.values()
+            if (field.source != '*') and ('.' not in field.source)
+        ])
+
+        validators = []
+        model_class = self.Meta.model
+
+        for unique_together in model_class._meta.unique_together:
+            if field_names.issuperset(set(unique_together)):
+                validator = UniqueTogetherValidator(
+                    queryset=model_class._default_manager,
+                    fields=unique_together
+                )
+                validator.serializer_field = self
+                validators.append(validator)
+
+        for parent_class in model_class._meta.parents.keys():
+            for unique_together in parent_class._meta.unique_together:
+                if field_names.issuperset(set(unique_together)):
+                    validator = UniqueTogetherValidator(
+                        queryset=parent_class._default_manager,
+                        fields=unique_together
+                    )
+                    validator.serializer_field = self
+                    validators.append(validator)
+
+        return validators
+
     def _get_base_fields(self):
         declared_fields = copy.deepcopy(self._declared_fields)
 

rest_framework/validators.py

@@ -1,18 +1,26 @@
+"""
+We perform uniqueness checks explicitly on the serializer class, rather
+the using Django's `.full_clean()`.
+
+This gives us better seperation of concerns, allows us to use single-step
+object creation, and makes it possible to switch between using the implicit
+`ModelSerializer` class and an equivelent explicit `Serializer` class.
+"""
 from django.core.exceptions import ValidationError
+from django.utils.translation import ugettext_lazy as _
+from rest_framework.utils.representation import smart_repr
 
 
 class UniqueValidator:
     # Validators with `requires_context` will have the field instance
     # passed to them when the field is instantiated.
     requires_context = True
+    message = _('This field must be unique.')
 
     def __init__(self, queryset):
         self.queryset = queryset
         self.serializer_field = None
 
-    def get_queryset(self):
-        return self.queryset.all()
-
     def __call__(self, value):
         field = self.serializer_field
 
@@ -24,15 +32,22 @@ class UniqueValidator:
 
         # Ensure uniqueness.
         filter_kwargs = {field_name: value}
-        queryset = self.get_queryset().filter(**filter_kwargs)
+        queryset = self.queryset.filter(**filter_kwargs)
         if instance:
             queryset = queryset.exclude(pk=instance.pk)
         if queryset.exists():
-            raise ValidationError('This field must be unique.')
+            raise ValidationError(self.message)
+
+    def __repr__(self):
+        return '<%s(queryset=%s)>' % (
+            self.__class__.__name__,
+            smart_repr(self.queryset)
+        )
 
 
 class UniqueTogetherValidator:
     requires_context = True
+    message = _('The fields {field_names} must make a unique set.')
 
     def __init__(self, queryset, fields):
         self.queryset = queryset
@@ -49,9 +64,16 @@ class UniqueTogetherValidator:
         filter_kwargs = dict([
             (field_name, value[field_name]) for field_name in self.fields
         ])
-        queryset = self.get_queryset().filter(**filter_kwargs)
+        queryset = self.queryset.filter(**filter_kwargs)
         if instance:
             queryset = queryset.exclude(pk=instance.pk)
         if queryset.exists():
-            field_names = ' and '.join(self.fields)
-            raise ValidationError('The fields %s must make a unique set.' % field_names)
+            field_names = ', '.join(self.fields)
+            raise ValidationError(self.message.format(field_names=field_names))
+
+    def __repr__(self):
+        return '<%s(queryset=%s, fields=%s)>' % (
+            self.__class__.__name__,
+            smart_repr(self.queryset),
+            smart_repr(self.fields)
+        )

tests/test_validators.py

@@ -3,33 +3,148 @@ from django.test import TestCase
 from rest_framework import serializers
 
 
-class ExampleModel(models.Model):
+def dedent(blocktext):
+    return '\n'.join([line[12:] for line in blocktext.splitlines()[1:-1]])
+
+
+# Tests for `UniqueValidator`
+# ---------------------------
+
+class UniquenessModel(models.Model):
     username = models.CharField(unique=True, max_length=100)
 
 
-class ExampleSerializer(serializers.ModelSerializer):
+class UniquenessSerializer(serializers.ModelSerializer):
     class Meta:
-        model = ExampleModel
+        model = UniquenessModel
 
 
 class TestUniquenessValidation(TestCase):
     def setUp(self):
-        self.instance = ExampleModel.objects.create(username='existing')
+        self.instance = UniquenessModel.objects.create(username='existing')
+
+    def test_repr(self):
+        serializer = UniquenessSerializer()
+        expected = dedent("""
+            UniquenessSerializer():
+                id = IntegerField(label='ID', read_only=True)
+                username = CharField(max_length=100, validators=[<UniqueValidator(queryset=UniquenessModel.objects.all())>])
+        """)
+        assert repr(serializer) == expected
 
     def test_is_not_unique(self):
         data = {'username': 'existing'}
-        serializer = ExampleSerializer(data=data)
+        serializer = UniquenessSerializer(data=data)
         assert not serializer.is_valid()
         assert serializer.errors == {'username': ['This field must be unique.']}
 
     def test_is_unique(self):
         data = {'username': 'other'}
-        serializer = ExampleSerializer(data=data)
+        serializer = UniquenessSerializer(data=data)
         assert serializer.is_valid()
         assert serializer.validated_data == {'username': 'other'}
 
     def test_updated_instance_excluded(self):
         data = {'username': 'existing'}
-        serializer = ExampleSerializer(self.instance, data=data)
+        serializer = UniquenessSerializer(self.instance, data=data)
         assert serializer.is_valid()
         assert serializer.validated_data == {'username': 'existing'}
+
+
+# Tests for `UniqueTogetherValidator`
+# -----------------------------------
+
+class UniquenessTogetherModel(models.Model):
+    race_name = models.CharField(max_length=100)
+    position = models.IntegerField()
+
+    class Meta:
+        unique_together = ('race_name', 'position')
+
+
+class UniquenessTogetherSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = UniquenessTogetherModel
+
+
+class TestUniquenessTogetherValidation(TestCase):
+    def setUp(self):
+        self.instance = UniquenessTogetherModel.objects.create(
+            race_name='example',
+            position=1
+        )
+        UniquenessTogetherModel.objects.create(
+            race_name='example',
+            position=2
+        )
+        UniquenessTogetherModel.objects.create(
+            race_name='other',
+            position=1
+        )
+
+    def test_repr(self):
+        serializer = UniquenessTogetherSerializer()
+        expected = dedent("""
+            UniquenessTogetherSerializer(validators=[<UniqueTogetherValidator(queryset=UniquenessTogetherModel.objects.all(), fields=('race_name', 'position'))>]):
+                id = IntegerField(label='ID', read_only=True)
+                race_name = CharField(max_length=100)
+                position = IntegerField()
+        """)
+        assert repr(serializer) == expected
+
+    def test_is_not_unique_together(self):
+        """
+        Failing unique together validation should result in non field errors.
+        """
+        data = {'race_name': 'example', 'position': 2}
+        serializer = UniquenessTogetherSerializer(data=data)
+        print serializer.validators
+        assert not serializer.is_valid()
+        assert serializer.errors == {
+            'non_field_errors': [
+                'The fields race_name, position must make a unique set.'
+            ]
+        }
+
+    def test_is_unique_together(self):
+        """
+        In a unique together validation, one field may be non-unique
+        so long as the set as a whole is unique.
+        """
+        data = {'race_name': 'other', 'position': 2}
+        serializer = UniquenessTogetherSerializer(data=data)
+        assert serializer.is_valid()
+        assert serializer.validated_data == {
+            'race_name': 'other',
+            'position': 2
+        }
+
+    def test_updated_instance_excluded_from_unique_together(self):
+        """
+        When performing an update, the existing instance does not count
+        as a match against uniqueness.
+        """
+        data = {'race_name': 'example', 'position': 1}
+        serializer = UniquenessTogetherSerializer(self.instance, data=data)
+        assert serializer.is_valid()
+        assert serializer.validated_data == {
+            'race_name': 'example',
+            'position': 1
+        }
+
+    def test_ignore_exlcuded_fields(self):
+        """
+        When model fields are not included in a serializer, then uniqueness
+        validtors should not be added for that field.
+        """
+        class ExcludedFieldSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = UniquenessTogetherModel
+                fields = ('id', 'race_name',)
+        serializer = ExcludedFieldSerializer()
+        expected = dedent("""
+            ExcludedFieldSerializer():
+                id = IntegerField(label='ID', read_only=True)
+                race_name = CharField(max_length=100)
+        """)
+        assert repr(serializer) == expected