OrderingFilter in rest framework 2.4.3

[Wei She]

Hi,

I don't know if anybody knows this problem, or if it is due to my misuse. The problem is:  with the filter 'OrderingFilter', I cannot sort queryset by a column of a referenced model. See the following example:

class Machine(models.Model):

    pool = models.ForeignKey('pool')

    ......

class Pool(models.Model):

    name = models.CharField(max_length=32)

    ...

Machine has a foreign key pointing to Pool, where Pool has a field called 'name'. What we want is to sort machines by the name of its pool. So I pass a parameter 'ordering=pool__name' from the URL (like http://.../machines?ordering=pool__name).

However, the queryset cannot be properly sorted. So I checked the source code. In /.../site-packages/rest_framework/filters.py, I saw two methods:

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156     def filter_queryset(self, request, queryset, view):

157         ordering = self.get_ordering(request)

158

159         if ordering:

160             # Skip any incorrect parameters

161             ordering = self.remove_invalid_fields(queryset, ordering, view)

162

163         if not ordering:

164             # Use 'ordering' attribute by default

165             ordering = self.get_default_ordering(view)

166

167         if ordering:

168             return queryset.order_by(*ordering)

169

170         return queryset

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134     def remove_invalid_fields(self, queryset, ordering, view):

135         valid_fields = getattr(view, 'ordering_fields', self.ordering_fields)

136

137         if valid_fields is None:

138             # Default to allowing filtering on serializer fields

139             serializer_class = getattr(view, 'serializer_class')

140             if serializer_class is None:

141                 msg = ("Cannot use %s on a view which does not have either a "

142                        "'serializer_class' or 'ordering_fields' attribute.")

143                 raise ImproperlyConfigured(msg % self.__class__.__name__)

144             valid_fields = [

145                 field.source or field_name

146                 for field_name, field in serializer_class().fields.items()

147                 if not getattr(field, 'write_only', False)

148             ]

149         elif valid_fields == '__all__':

150             # View explictly allows filtering on any model field

151             valid_fields = [field.name for field in queryset.model._meta.fields]

152             valid_fields += queryset.query.aggregates.keys()

153

154         return [term for term in ordering if term.lstrip('-') in valid_fields]

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As you can see, filter_queryset is based on "order_by" which will accept Django style, e.g. using "order_by('pool__name')". However, if I pass 'pool__name' into this method, it hits method 'remove_invalid_fields' and gets removed.

The problem is at line 151. Here, the model's fields are extracted. Therefore, 'pool_name' gets removed.

Anybody knows how to fix it, except letting me override filter_queryset again?

Thanks,

Wei