update create new within update

misc/utils.py

@@ -11,6 +11,8 @@ class SaveFileObject():
     def asdict(self):
         return asdict(self)
     def update(self, new):
+        if new is None:
+            new=dict()
         for key, value in new.items():
             if hasattr(self, key):
                 setattr(self, key, value)
@@ -57,7 +59,7 @@ class SaveFileMapping(Mapping):
         if not isinstance(data,SaveFileObject):
             raise TypeError("data elements should be derived from SaveFileObject")
         if not callable(getattr(data,"asdict",None)):
-            raise TypeError("Dataelements need a method to_dict that returns a dict")
+            raise TypeError("Dataelements need a method asdict that returns a dict this should be out of the box if you use dataclasses")
         #if not callable(getattr(data.__class__,"from_dict",None)):
         #    raise TypeError("Dataelements need a method to_dict that returns a dict")