Fixed OrderingFilter handling of empty values. (#1628)

A trailing comma would cause a crash trying to map an empty value to a
field name. Ensure sub-values are filtered for EMPTY_VALUES in
addition to the main filter data.

Closes #1597.

Co-authored-by: munnsmunns <mmunns16@gmail.com>

django_filters/filters.py

@@ -759,7 +759,11 @@ def filter(self, qs, value):
         if value in EMPTY_VALUES:
             return qs
 
-        ordering = [self.get_ordering_value(param) for param in value]
+        ordering = [
+            self.get_ordering_value(param)
+            for param in value
+            if param not in EMPTY_VALUES
+        ]
         return qs.order_by(*ordering)
 
     @classmethod

tests/test_filtering.py

@@ -1976,9 +1976,15 @@ class Meta:
                 fields = ["username"]
 
         qs = User.objects.all()
-        f = F({"o": "username"}, queryset=qs)
-        names = f.qs.values_list("username", flat=True)
-        self.assertEqual(list(names), ["aaron", "alex", "carl", "jacob"])
+        tests = [
+            {"o": "username"},
+            QueryDict("o=username,"),
+        ]
+        for data in tests:
+            with self.subTest(data=data):
+                f = F(data, queryset=qs)
+                names = f.qs.values_list("username", flat=True)
+                self.assertEqual(list(names), ["aaron", "alex", "carl", "jacob"])
 
     def test_ordering_with_select_widget(self):
         class F(FilterSet):
@@ -1993,6 +1999,27 @@ class Meta:
         names = f.qs.values_list("username", flat=True)
         self.assertEqual(list(names), ["aaron", "alex", "carl", "jacob"])
 
+    def test_csv_input(self):
+        class F(FilterSet):
+            o = OrderingFilter(widget=forms.Select, fields=("username",),)
+
+            class Meta:
+                model = User
+                fields = ["username"]
+
+        qs = User.objects.all()
+        tests = [
+            {"o": ","},
+            QueryDict("o=%2c"),
+            QueryDict("o=,"),
+        ]
+        for data in tests:
+            with self.subTest(data=data):
+                f = F(data, queryset=qs)
+                self.assertIs(True, f.is_valid())
+                names = f.qs.values_list("username", flat=True)
+                self.assertEqual(list(names), ['alex', 'jacob', 'aaron', 'carl'])
+
 
 class MiscFilterSetTests(TestCase):
     def setUp(self):