- Fixed bug in association proxy where assigning an empty slice

(e.g. ``x[:] = [...]``) would fail on Py3k.

doc/build/changelog/changelog_09.rst

@@ -14,6 +14,12 @@
 .. changelog::
     :version: 0.9.4
 
+    .. change::
+        :tags: bug, ext, py3k
+
+        Fixed bug in association proxy where assigning an empty slice
+        (e.g. ``x[:] = [...]``) would fail on Py3k.
+
     .. change::
         :tags: bug, general
         :tickets: 2979

lib/sqlalchemy/ext/associationproxy.py

@@ -540,11 +540,12 @@ class _AssociationList(_AssociationCollection):
                 stop = index.stop
             step = index.step or 1
 
+            start = index.start or 0
             rng = list(range(index.start or 0, stop, step))
             if step == 1:
                 for i in rng:
-                    del self[index.start]
-                i = index.start
+                    del self[start]
+                i = start
                 for item in value:
                     self.insert(i, item)
                     i += 1

test/ext/test_associationproxy.py

@@ -212,6 +212,13 @@ class _CollectionOperations(fixtures.TestBase):
         self.assert_(p1.children == after)
         self.assert_([c.name for c in p1._children] == after)
 
+        p1.children[:] = ['d', 'e']
+        after = ['d', 'e']
+        self.assert_(p1.children == after)
+        self.assert_([c.name for c in p1._children] == after)
+
+        p1.children[:] = ['a', 'b']
+
         p1.children += ['c']
         after = ['a', 'b', 'c']
         self.assert_(p1.children == after)