Neal Becker <[email protected]> writes: > ... > Has anyone else run into this issue
People who use the "ZODB" (= "Zope Object DataBase") are familiar with it. > and have any ideas? There are things, you must not do. In the "ZODB" case, for example, you must not change whether the class inherits from "persistent.Persistent" or not. For other things, there are workarounds: * you can use "module" aliases and/or class aliases inside a module to handle changes in the package/class structure * you can register a "class factory" to provide a "default class" for a class not found -- this way, you have at least access to the data event though the replacement class does not understand it. * if a (new) class is found, it must be able to cope with the (old) data. You may need to provide an appropriate "__setstate__" in the (new) class to make this possible. * objects created from old data may lack attributes which objects created after a class change have. You can either add them in "__setstate__" or provide default values in the class * if you plan drastical changes, migrate your data using a different serialization. An example is e.g. a switch from "ZODB on Python 2" to "ZODB on Python 3". One approach in this case is to use "collective.transmogrifier". See "https://docs.plone.org/develop/import/index.html#collective-transmogrifier"; for details. -- https://mail.python.org/mailman/listinfo/python-list
