How to write dictionary to a text file properly

July 9, 2022

I am trying to create a text file with dictionary storing some value so that I can retrieve it later but the write creates multiple dictionary how can I create only a single dictionary also the type of data is returned is as string how can I use it as dictionary, kindly pardon I am new to python,

I tried with json dump method but I was getting typeerror-object-of-type-method-is-not-json-serializable

import json

mydic = {}

for i in range(3):
    uname = input("enter uname\n")
    pwd = input("enter pwd\n")

    mydic[uname] = pwd

print(mydic)


with open("cd.txt","a+") as file:
    file.write(str(mydic))


with open("cd.txt","r") as file:
    data = file.read()
    print(data,type(data))

Data is getting saved as below 1-3 I gave input in first attempt 4 -6 for second attempt U can see 2 different dictionay got created

{'1': '1', '2': '2', '3': '3'}{'4': '4', '5': '5', '6': '6'}

>Solution :

You are adding the string conversion of your dictionary onto the file. Each time you run your program, the a+ flag tells it to append as a string.

You can fix this by using a json format–like you imported:

import json

mydic = {}

# Read existing data
with open('cd.json', 'r') as jsonFile:
    mydic = json.load(jsonFile)

# Get usernames and passwords
for i in range(3):
    uname = input("enter uname\n")
    pwd = input("enter pwd\n")

    mydic[uname] = pwd

print(mydic)


# Write new values
with open('cd.json', 'w') as jsonFile:   
    json.dump(mydic, jsonFile, indent=4, sort_keys=True)

First we read the existing values, then we run through the code you wrote to get usernames and passwords, and finally, we save all the data to a json file.