First pass at unique_for_date, unique_for_month, unique_for_year

1 files changed, 99 insertions, 22 deletions

diff --git a/rest_framework/validators.py b/rest_framework/validators.py
index f76faaa4..e302a0e4 100644
--- a/rest_framework/validators.py
+++ b/rest_framework/validators.py
@@ -6,38 +6,36 @@ This gives us better separation 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.exceptions import ValidationError
 from rest_framework.utils.representation import smart_repr
 
 
 class UniqueValidator:
     """
     Validator that corresponds to `unique=True` on a model field.
+
+    Should be applied to an individual field on the serializer.
     """
-    # 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 __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
-
+    def set_context(self, serializer_field):
+        # Determine the underlying model field name. This may not be the
+        # same as the serializer field name if `source=<>` is set.
+        self.field_name = serializer_field.source_attrs[0]
         # Determine the existing instance, if this is an update operation.
-        instance = getattr(field.parent, 'instance', None)
+        self.instance = getattr(serializer_field.parent, 'instance', None)
 
+    def __call__(self, value):
         # Ensure uniqueness.
-        filter_kwargs = {field_name: value}
+        filter_kwargs = {self.field_name: value}
         queryset = self.queryset.filter(**filter_kwargs)
-        if instance:
-            queryset = queryset.exclude(pk=instance.pk)
+        if self.instance is not None:
+            queryset = queryset.exclude(pk=self.instance.pk)
         if queryset.exists():
             raise ValidationError(self.message)
 
@@ -51,8 +49,9 @@ class UniqueValidator:
 class UniqueTogetherValidator:
     """
     Validator that corresponds to `unique_together = (...)` on a model class.
+
+    Should be applied to the serializer class, not to an individual field.
     """
-    requires_context = True
     message = _('The fields {field_names} must make a unique set.')
 
     def __init__(self, queryset, fields):
@@ -60,19 +59,18 @@ class UniqueTogetherValidator:
         self.fields = fields
         self.serializer_field = None
 
-    def __call__(self, value):
-        serializer = self.serializer_field
-
+    def set_context(self, serializer):
         # Determine the existing instance, if this is an update operation.
-        instance = getattr(serializer, 'instance', None)
+        self.instance = getattr(serializer, 'instance', None)
 
+    def __call__(self, attrs):
         # Ensure uniqueness.
         filter_kwargs = dict([
-            (field_name, value[field_name]) for field_name in self.fields
+            (field_name, attrs[field_name]) for field_name in self.fields
         ])
         queryset = self.queryset.filter(**filter_kwargs)
-        if instance:
-            queryset = queryset.exclude(pk=instance.pk)
+        if self.instance is not None:
+            queryset = queryset.exclude(pk=self.instance.pk)
         if queryset.exists():
             field_names = ', '.join(self.fields)
             raise ValidationError(self.message.format(field_names=field_names))
@@ -83,3 +81,82 @@ class UniqueTogetherValidator:
             smart_repr(self.queryset),
             smart_repr(self.fields)
         )
+
+
+class BaseUniqueForValidator:
+    message = None
+
+    def __init__(self, queryset, field, date_field):
+        self.queryset = queryset
+        self.field = field
+        self.date_field = date_field
+
+    def set_context(self, serializer):
+        # Determine the underlying model field names. These may not be the
+        # same as the serializer field names if `source=<>` is set.
+        self.field_name = serializer.fields[self.field].source_attrs[0]
+        self.date_field_name = serializer.fields[self.date_field].source_attrs[0]
+        # Determine the existing instance, if this is an update operation.
+        self.instance = getattr(serializer, 'instance', None)
+
+    def get_filter_kwargs(self, attrs):
+        raise NotImplementedError('`get_filter_kwargs` must be implemented.')
+
+    def __call__(self, attrs):
+        filter_kwargs = self.get_filter_kwargs(attrs)
+
+        queryset = self.queryset.filter(**filter_kwargs)
+        if self.instance is not None:
+            queryset = queryset.exclude(pk=self.instance.pk)
+        if queryset.exists():
+            message = self.message.format(date_field=self.date_field)
+            raise ValidationError({self.field: message})
+
+    def __repr__(self):
+        return '<%s(queryset=%s, field=%s, date_field=%s)>' % (
+            self.__class__.__name__,
+            smart_repr(self.queryset),
+            smart_repr(self.field),
+            smart_repr(self.date_field)
+        )
+
+
+class UniqueForDateValidator(BaseUniqueForValidator):
+    message = _('This field must be unique for the "{date_field}" date.')
+
+    def get_filter_kwargs(self, attrs):
+        value = attrs[self.field]
+        date = attrs[self.date_field]
+
+        filter_kwargs = {}
+        filter_kwargs[self.field_name] = value
+        filter_kwargs['%s__day' % self.date_field_name] = date.day
+        filter_kwargs['%s__month' % self.date_field_name] = date.month
+        filter_kwargs['%s__year' % self.date_field_name] = date.year
+        return filter_kwargs
+
+
+class UniqueForMonthValidator(BaseUniqueForValidator):
+    message = _('This field must be unique for the "{date_field}" month.')
+
+    def get_filter_kwargs(self, attrs):
+        value = attrs[self.field]
+        date = attrs[self.date_field]
+
+        filter_kwargs = {}
+        filter_kwargs[self.field_name] = value
+        filter_kwargs['%s__month' % self.date_field_name] = date.month
+        return filter_kwargs
+
+
+class UniqueForYearValidator(BaseUniqueForValidator):
+    message = _('This field must be unique for the "{date_field}" year.')
+
+    def get_filter_kwargs(self, attrs):
+        value = attrs[self.field]
+        date = attrs[self.date_field]
+
+        filter_kwargs = {}
+        filter_kwargs[self.field_name] = value
+        filter_kwargs['%s__year' % self.date_field_name] = date.year
+        return filter_kwargs