How to write dictionary to a text file properly-CodePudding

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'}

CodePudding user response：

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.

CodePudding user response：

You need to handle the content in the file as JSON, that's the easiest way to update the content, not handling as string version of dictionnary that you would append

I used pathlib.Path to facilitate the file interactions

import json
from pathlib import Path

file = Path("cd.json")

if file.exists():  # load existing data
    mydic = json.loads(file.read_text())
else:  # create new
    mydic = {}

# add more data
for i in range(3):
    uname = input("enter uname\n")
    pwd = input("enter pwd\n")
    mydic[uname] = pwd

print(mydic)

# save in file
file.write_text(json.dumps(mydic))

# load back to verify
mydic = json.loads(file.read_text())
print(mydic)

CodePudding user response：

Try writing the dictionary as Pandas Dataframe in a csv file. It's much simpler to write and read from an csv file. And in future if you are having multiple dictionaries then you can just make a list of dicts and write to the csv file.

import pandas as pd

df=pd.DataFrame([your_dictionary])
df.to_csv(file_name)

#read csv
read_df = pd.read_csv(file_name)
dict_list=read_df.to_dict('records')  #this will give you the list of dictionaries