如何从具有多个键的字典中转储一个值到 json 以写入文件

Question

I have a dictionary. It has 2 keys for 1 value. Multiple items are inside. I want to dump it to json for the purpose of writing to file. When I try below code, I get nothing. What is your suggestion for this operation?

def __init__(self):
   self.news_dict = {}


def add_to_dict(self, newspaper, topic, news):

   if not (newspaper,topic) in self.news_dict:
       self.news_dict[newspaper,topic] = []

   if not news in self.news_dict[newspaper,topic]:
       self.news_dict[newspaper,topic].append(news)

.... in another part of code

for descriptions in data["result"]:
    self.add_to_dict(descriptions["source"], category, descriptions["description"])

output_writing = json.dumps(self.news_dict)
print(output_writing)

with open(os.path.dirname(os.path.abspath(__file__)) + '/record.json', "w") as json_file:
    json.dump(output_writing, json_file) 

# read json string
with open(os.path.dirname(os.path.abspath(__file__)) + '/record.json') as json_file:
     output_reading = json.load(json_file)

# json string to dic
output_reading = json.loads(output_reading)

Answer 1

Your fundamental problem is that Python dictionaries can have data structures as keys, but JSON hashes require keys to be strings. There is therefore no way to represent the Python structure as JSON.

If you just need a way to serialize/deserialize data, you can use pickle . If you want it to be human readable, you need to write a custom serialization module.

If you want it to look like JSON, your best bet is to write a custom function that converts your data structure into one where every key has been converted to a string that is your custom JSON representation of the data structure, and then convert THAT into JSON. It won't be pretty, and also in deserializing it you will have to reverse the process.