如何将键：值对添加到简单的 JSON 文件

Question

JSON

{
    "user1": "password1",
    "user2": "password2"
}

Code

So let's say I have one new user, user3 I'll store his password and username into two different variables

username = "user3"
password = "password3"

Output Goal

I'd like my JSON file to finally look like this:

{
    "user1": "password1",
    "user2": "password2",
    "user3": "password3
}

Answer 1

Just parse you json into a dict, add the key/value pair and dump it back to a json string:

import json

j = '''{
    "user1": "password1",
    "user2": "password2"
}'''

username = "user3"
password = "password3"

my_dict = json.loads(j)
my_dict[username] = password

json.dumps(my_dict)
# '{"user1": "password1", "user2": "password2", "user3": "password3"}'

If you starting from a file, it's basically the same — just open the file and use load() and dump() . Something like:

import json

path = "/path/to/file.txt"
outpath = "/path/to/output_file.txt"

username = "user3"
password = "password3"

with open(path) as json_file:
    my_dict = json.load(json_file)

my_dict[username] = password

with open(outpath, 'w') as json_file:
    json.dump(my_dict, json_file)