1 files changed, 57 insertions, 0 deletions
diff --git a/rest_framework/validators.py b/rest_framework/validators.py
new file mode 100644
index 00000000..f5fbeb3c
--- /dev/null
+++ b/rest_framework/validators.py
@@ -0,0 +1,57 @@
+from django.core.exceptions import ValidationError
+
+
+class UniqueValidator:
+    # Validators with `requires_context` will have the field instance
+    # passed to them when the field is instantiated.
+    requires_context = True
+
+    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
+
+        # Determine the model field name that the serializer field corresponds to.
+        field_name = field.source_attrs[0] if field.source_attrs else field.field_name
+
+        # Determine the existing instance, if this is an update operation.
+        instance = getattr(field.parent, 'instance', None)
+
+        # Ensure uniqueness.
+        filter_kwargs = {field_name: value}
+        queryset = self.get_queryset().filter(**filter_kwargs)
+        if instance:
+            queryset = queryset.exclude(pk=instance.pk)
+        if queryset.exists():
+            raise ValidationError('This field must be unique.')
+
+
+class UniqueTogetherValidator:
+    requires_context = True
+
+    def __init__(self, queryset, fields):
+        self.queryset = queryset
+        self.fields = fields
+        self.serializer_field = None
+
+    def __call__(self, value):
+        serializer = self.serializer_field
+
+        # Determine the existing instance, if this is an update operation.
+        instance = getattr(serializer, 'instance', None)
+
+        # Ensure uniqueness.
+        filter_kwargs = dict([
+            (field_name, value[field_name]) for field_name in self.fields
+        ])
+        queryset = self.get_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)