Python: Pickle Misbehaving In Django Shell As Opposed To Python Shell?
Solution 1:
pickle
will make sure it can re-import a class, as only the data on the instance itself is pickled, plus the import location of the class. As such, pickle
looks for the __module__
attribute on the class to determine where it came from.
It appears the Django interactive environment does not set this __module__
attribute; as a result TestObj.__module__
is inherited from the object
base class instead, and that's __builtin__
. Perhaps no __name__
global is set. As a result, the pickle
module ends up looking in the wrong place for your class. There is no __builtin__.TestObj
after all.
From the comments, I gather that you are trying to store mocked objects in the Django cache. That won't work, as mock objects are not pickleable. That makes sense, as on unpickling (which could be in an entirely new Python process), how would pickle
know what original class was being mocked?
Solution 2:
Could you not just use a serializer that doesn't pickle classes by reference… and then pre-serialize what you pass into the django cache? This would store not only the instance, but also the class definition itself -- which should allow you to reconstruct the instance anywhere.
See my answer on your original question: Pickle can't store an object in django locmem cache during tests?
I don't know anything about django Mock objects, or if there's something especially unpicklable about them… But as long as they are built from python code (as opposed to built in C, and have a thin python wrapper layer), then the above should likely work.
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