Added OrderingFilter

2 files changed, 156 insertions, 1 deletions

diff --git a/rest_framework/filters.py b/rest_framework/filters.py
index c496ec4b..308e7da2 100644
--- a/rest_framework/filters.py
+++ b/rest_framework/filters.py
@@ -4,7 +4,7 @@ returned by list views.
 """
 from __future__ import unicode_literals
 from django.db import models
-from rest_framework.compat import django_filters
+from rest_framework.compat import django_filters, six
 from functools import reduce
 import operator
 
@@ -109,3 +109,42 @@ class SearchFilter(BaseFilterBackend):
             queryset = queryset.filter(reduce(operator.or_, or_queries))
 
         return queryset
+
+
+class OrderingFilter(BaseFilterBackend):
+    ordering_param = 'order'  # The URL query parameter used for the ordering.
+
+    def get_ordering(self, request):
+        """
+        Search terms are set by a ?search=... query parameter,
+        and may be comma and/or whitespace delimited.
+        """
+        params = request.QUERY_PARAMS.get(self.ordering_param)
+        if params:
+            return [param.strip() for param in params.split(',')]
+
+    def get_default_ordering(self, view):
+        ordering = getattr(view, 'ordering', None)
+        if isinstance(ordering, six.string_types):
+            return (ordering,)
+        return ordering
+
+    def remove_invalid_fields(self, queryset, ordering):
+        field_names = [field.name for field in queryset.model._meta.fields]
+        return [term for term in ordering if term.lstrip('-') in field_names]
+
+    def filter_queryset(self, request, queryset, view):
+        ordering = self.get_ordering(request)
+
+        if ordering:
+            # Skip any incorrect parameters
+            ordering = self.remove_invalid_fields(queryset, ordering)
+
+        if not ordering:
+            # Use 'ordering' attribtue by default
+            ordering = self.get_default_ordering(view)
+
+        if ordering:
+            return queryset.order_by(*ordering)
+
+        return queryset
diff --git a/rest_framework/tests/filters.py b/rest_framework/tests/filters.py
index e5414232..6b604deb 100644
--- a/rest_framework/tests/filters.py
+++ b/rest_framework/tests/filters.py
@@ -335,3 +335,119 @@ class SearchFilterTests(TestCase):
                 {'id': 2, 'title': 'zz', 'text': 'bcd'}
             ]
         )
+
+
+class OrdringFilterModel(models.Model):
+    title = models.CharField(max_length=20)
+    text = models.CharField(max_length=100)
+
+
+class OrderingFilterTests(TestCase):
+    def setUp(self):
+        # Sequence of title/text is:
+        #
+        # zyx abc
+        # yxw bcd
+        # xwv cde
+        for idx in range(3):
+            title = (
+                chr(ord('z') - idx) +
+                chr(ord('y') - idx) +
+                chr(ord('x') - idx)
+            )
+            text = (
+                chr(idx + ord('a')) +
+                chr(idx + ord('b')) +
+                chr(idx + ord('c'))
+            )
+            OrdringFilterModel(title=title, text=text).save()
+
+    def test_ordering(self):
+        class OrderingListView(generics.ListAPIView):
+            model = OrdringFilterModel
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+
+        view = OrderingListView.as_view()
+        request = factory.get('?order=text')
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+            ]
+        )
+
+    def test_reverse_ordering(self):
+        class OrderingListView(generics.ListAPIView):
+            model = OrdringFilterModel
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+
+        view = OrderingListView.as_view()
+        request = factory.get('?order=-text')
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+            ]
+        )
+
+    def test_incorrectfield_ordering(self):
+        class OrderingListView(generics.ListAPIView):
+            model = OrdringFilterModel
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+
+        view = OrderingListView.as_view()
+        request = factory.get('?order=foobar')
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+            ]
+        )
+
+    def test_default_ordering(self):
+        class OrderingListView(generics.ListAPIView):
+            model = OrdringFilterModel
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+
+        view = OrderingListView.as_view()
+        request = factory.get('')
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+            ]
+        )
+
+    def test_default_ordering_using_string(self):
+        class OrderingListView(generics.ListAPIView):
+            model = OrdringFilterModel
+            filter_backends = (filters.OrderingFilter,)
+            ordering = 'title'
+
+        view = OrderingListView.as_view()
+        request = factory.get('')
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+            ]
+        )