          queryset = self.filter_queryset(attrs, queryset)
          queryset = self.exclude_current_instance(attrs, queryset)
  
          # Ignore validation if any field is None
          if None not in attrs.values() and queryset.exists():
              field_names = ', '.join(self.fields)
              raise ValidationError(self.message.format(field_names=field_names))
  
      def __repr__(self):
          return unicode_to_repr('<%s(queryset=%s, fields=%s)>' % (
 
</s> remove         data = {'race_name': None, 'position': None}
        serializer = UniquenessTogetherSerializer(data=data)

 </s> add         data = {
            'date': datetime.date(2000, 1, 1),
            'race_name': 'Paris Marathon',
            'position': None
        }
        serializer = NullUniquenessTogetherSerializer(data=data) </s> remove         UniquenessTogetherModel.objects.create(
            race_name=None,
 </s> add         # None values that are on fields which are part of the uniqueness
        # constraint cause the instance to ignore uniqueness validation.
        NullUniquenessTogetherModel.objects.create(
            date_of_birth=datetime.date(2000, 1, 1),
            race_name='Paris Marathon',
        checked_values = [
            value for field, value in attrs.items() if field in self.fields
        ]
        if None not in checked_values and queryset.exists():
          queryset = self.filter_queryset(attrs, queryset)
          queryset = self.exclude_current_instance(attrs, queryset)
  
          # Ignore validation if any field is None
        checked_values = [
            value for field, value in attrs.items() if field in self.fields
        ]
        if None not in checked_values and queryset.exists():
              field_names = ', '.join(self.fields)
              raise ValidationError(self.message.format(field_names=field_names))
  
      def __repr__(self):
          return unicode_to_repr('<%s(queryset=%s, fields=%s)>' % (
keep keep keep keep replace keep keep keep keep keep
 Skip validation of NULL field only if it part of unique_together 
rest_framework/validators.py