return None in Movement.getExplanationValue if getRootDeliveryValue is...

return None in Movement.getExplanationValue if getRootDeliveryValue is missing, because we use Movement class as the base class for non Delivery->Movement structure classes too.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@38279 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/Movement.py

@@ -554,7 +554,10 @@ class Movement(XMLObject, Amount, CompositionMixin):
     """
       Returns the object explanation of this movement.
     """
-    return self.getRootDeliveryValue()
+    try:
+      return self.getRootDeliveryValue()
+    except AttributeError:
+      return None
  
   security.declareProtected( Permissions.AccessContentsInformation,
                              'getExplanationTitle')