diff -r a82f83188695 -r cf79af56fed0 web/widgets.py
--- a/web/widgets.py	Thu Apr 09 16:17:16 2009 +0200
+++ b/web/widgets.py	Thu Apr 09 16:25:29 2009 +0200
@@ -839,7 +839,7 @@
         eclass, subjschema = _eclass_eschema(subjschema)
     else:
         eclass, objschema = _eclass_eschema(objschema)
-    if eclass is not None and rschema in eclass.widgets:
+    if eclass is not None and rschema in getattr(eclass, 'widgets', ()):
         wcls = WIDGETS[eclass.widgets[rschema]]
     elif not rschema.is_final():
         card = rschema.rproperty(subjschema, objschema, 'cardinality')