使用Python在JSON文件中追加列表

Question

I'm trying to append a list with new names in a json file.

JSON structure:

{
    "users": [
        "User1",
        "User2",
        "User3"
    ]
}

I have tried this:

with open('data/users.json', 'r') as json_file:
    json_data = json.load(json_file)
    user_list = json_data["users"]
 with open('data/users.json', 'w') as json_file:
    user_list.append(name)
    json.dump(user_list, json_file)

But it turns out like this:

["User1", "User2", "User3", "User4"]

Why and how do I fix it?

Answer 1

You need to write the whole data dictionary, not just the list

with open('data/users.json', 'r') as json_file:
    json_data = json.load(json_file)
    json_data["users"].append(name)
with open('data/users.json', 'w') as json_file:
    json.dump(json_data, json_file)