PYTHON-700 - Support subclassing of son manipulators

pymongo/database.py

@@ -29,6 +29,7 @@ from pymongo.errors import (CollectionInvalid,
 from pymongo.read_preferences import (modes,
                                       secondary_ok_commands,
                                       ReadPreference)
+from pymongo.son_manipulator import SONManipulator
 
 
 def _check_name(name):
@@ -94,9 +95,10 @@ class Database(common.BaseObject):
         :Parameters:
           - `manipulator`: the manipulator to add
         """
+        base = SONManipulator()
         def method_overwritten(instance, method):
-            return getattr(instance, method) != \
-                getattr(super(instance.__class__, instance), method)
+            return (getattr(
+                instance, method).im_func != getattr(base, method).im_func)
 
         if manipulator.will_copy():
             if method_overwritten(manipulator, "transform_incoming"):

test/test_database.py

@@ -707,6 +707,30 @@ class TestDatabase(unittest.TestCase):
         out = db.test.find_one()
         self.assertEqual('value', out.get('value'))
 
+    def test_son_manipulator_inheritance(self):
+        class Thing(object):
+            def __init__(self, value):
+                self.value = value
+
+        class ThingTransformer(SONManipulator):
+            def transform_incoming(self, thing, collection):
+                return {'value': thing.value}
+
+            def transform_outgoing(self, son, collection):
+                return Thing(son['value'])
+
+        class Child(ThingTransformer):
+            pass
+
+        db = self.client.foo
+        db.add_son_manipulator(Child())
+        t = Thing('value')
+
+        db.test.remove()
+        db.test.insert([t])
+        out = db.test.find_one()
+        self.assertTrue(isinstance(out, Thing))
+        self.assertEqual('value', out.value)
 
 if __name__ == "__main__":
     unittest.main()