JSON Dump and JSON Load

[buran]

I see the discussion has evolved since I first read this thread in the morning.
Although you think you has resolved the problem, I strongly advise you to read

How to make a class JSON serializable

How to convert JSON data into a Python object?

Using pickle may work, but you should be aware there some security risks. Check the Warning at the top of pickle module docs

Also, couple of style issues with your code - don't use dumps and loads, json.dump and json.load will do

    with open(fxWarMapList, "w") as :
        outfile.dump(fxWarConquest.fxWarMaps.maps, outfile, default=lambda x: x.__dict__, indent=4)

with open(fxWarMapList, 'r') as j:
     fxWarConquest.fxWarMaps.maps = json.load(j)