python从1个平面字典到嵌套字典中提取数据

Question

I'm trying write a function that can extract data from a larger dictionary to be put in a smaller nested dict (that will ultimately be a payload in a request). I have just put the payload dict structure with None and the default values with the data to be populated from info_json. However I get a error "dictionary changed size during iteration"

def extract_payload(self, info_json):
        info_dict = json.loads(info_json)
        payload = {"service": None, "current": None,
                   "product1": {"id": None, "id2": None,
                                        "name": None,
                                        "method": "constant_value"},
                   "product2": {"id": None, "id2": None,
                                                "name": None,
                                                "method": None, "always_false": False},
                   "usage": {"usage1": None, "usage2": None, "usage3": None,
                                   "usage4": 2066}

        for key,value in payload.items():
            if value is not None:
                for sub_key in value: 
                    value = info_dict.get(sub_key)
                    payload['sub_key'] = value
            else:
                value = info_dict.get(key)
                payload['key'] = value
        return payload

Answer 1

There is a missing } at the end of payload. You are overwriting payload['sub_key'] the same time for each loop, it needs to be payload[sub_key] , same for else payload[key] = value