Allow __exact lookups

taggit/managers.py

@@ -44,8 +44,10 @@ class TaggableManager(object):
         pass
     
     def get_db_prep_lookup(self, lookup_type, value):
-        if lookup_type != "in":
-            raise ValueError("You can't do lookups other than in on Tags")
+        if lookup_type not in  ("in", "exact"):
+            raise ValueError("You can't do lookups other than \"in\" and \"exact\" on Tags")
+        if lookup_type == "exact":
+            value = [value]
         qs = TaggedItem.objects.filter(tag__name__in=value).values_list("pk", flat=True)
         sql, params = qs.query.as_sql()
         return QueryWrapper(("(%s)" % sql), params)

taggit/tests/tests.py

@@ -53,6 +53,8 @@ class LookupByTagTestCase(BaseTaggingTest):
         dog.tags.add("woof", "red")
         self.assertEqual(list(Food.objects.filter(tags__in=["red"]).distinct()), [apple])
 
+        self.assertEqual(list(Food.objects.filter(tags="red").distinct()), [apple])
+
 
 class TaggableFormTestCase(BaseTaggingTest):
     def test_form(self):