Storing instances using jsonpickle
ned at nedbatchelder.com
Wed Sep 3 22:52:50 CEST 2014
On 9/3/14 4:32 PM, Josh English wrote:
> I am using jsonpickle to store instances of an object into separate data files.
> If I make any changes to the original class definition of the object, when I recreate my stored instances, they are recreated using the original class definition, so any new attributes, methods, or properties, are lost.
> I think this is happening because JSON is internalizing the class definition, ignoring the updates. Is this true? Is it possible to refresh JSON's knowledge of a class?
Pickle (and it looks like jsonpickle) does not invoke the class'
__init__ method when it reconstitutes objects. Your new __init__ is not
being run, so new attributes it defines are not being created.
This is one of the reasons that people avoid pickle: being completely
implicit is very handy, but also fragile.
Ned Batchelder, http://nedbatchelder.com
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