如何使该实体序列化/反序列化？

Question

The code below defines a dictionary used to transform field values. Data is read, some of the values are transformed based on this dictionary, and written to a table. It works as-is. The problem, I now want to move this configuration outside the .py file into a JSON configuration file.

 lookups = {
     11: {
         "ST1": ["ABC"],
         "UNK01": ["125", "ACD"],
         "A": ["52"],
         "B": ["91"],
         "C": ["92"],
         "D": ["95"]
        },
     10: {
         "XYZ01": ["91"],
         "XYZ02": ["83"],
         "XYZ03": ["27"]
        }
 }

According to jsonlint.com, in order for the above value being assigned to lookups to be valid JSON, I must quote the 11 and 10 keys. Doing so breaks my Python code and displays TypeError: list indices must be integers, not str .

How do I create valid JSON and minimize changes to my code?

Answer 1

If you want to dump it to a json file:

import json 

with open("config.json","w") as f:
    json.dump(lookups, f) # dump dict to file

with open("config.json") as f:
    s = json.load(f) # load dict from file
print(s)
{'11': {'ST1': ['ABC'], 'A': ['52'], 'D': ['95'], 'UNK01': ['125', 'ACD'], 'B': ['91'], 'C': ['92']}, '10': {'XYZ01': ['91'], 'XYZ03': ['27'], 'XYZ02': ['83']}}

If you need keys as ints you can loop and cast as ints or use pickle :

import pickle
with open("in.pkl","wb") as f:
    pickle.dump(lookups, f)

with open("in.pkl","rb") as f:
    s = pickle.load(f)
print(s)
{10: {'XYZ03': ['27'], 'XYZ01': ['91'], 'XYZ02': ['83']}, 11: {'UNK01': ['125', 'ACD'], 'B': ['91'], 'D': ['95'], 'ST1': ['ABC'], 'C': ['92'], 'A': ['52']}}

If not just use as is.

Answer 2

If you know what type of data your keys are, a simple int on the keys would suffice:

dictionary_from_json = json.loads(dumped)
newdict = {}
for key, val in dictionary_from_json:
    newdict[int(key)] = val

Answer 3

You can extend json.decoder and convert all keys to int when it's possible.

import json
class Json(json.JSONDecoder):
    def decode(self,json_string):
        default_obj = super(Json,self).decode(json_string)
        new_obj = self._rec_serial(default_obj)
        return new_obj

    def _rec_serial(self,default):
        new_dict = {}
        for key,value in default.items():
            is_dict = isinstance(value,dict)
            value = self._rec_serial(value) if is_dict else value
            try:
                new_dict[int(key)] = value
            except ValueError:
                new_dict[key] = value
        return new_dict

json2= Json()
d = json2.decode(dumped)