Login simulation. Dictionary with [“username”]: [“password”] key:value pairs. How do I authenticate a user trying to log in?

Inside of a json file, each line stores the information of every different user that is created through separate classes. In the user_login file, retrieves this info and isolates username and passwords for each user to attempt to create a login page.

user_login

File: user_login

user_login

import json

filename = "users.json"
with open(filename, "r+", encoding='utf8') as file:
'''opens json file and separates it by line by storing each line into an
array'''
lines = file.readlines()

login_info =
'''array that will store usernames and passwords for each user(each line in
the file is a user)'''

for line in lines:
'''simply prints each element of the lines array displaying the
information of each user'''
info = json.loads(line)
print("USER: " + str(info))
print("username: " + info["username"])
print("password: " + info["password"] + "n")
login_info[info["username"]] = info["password"]
'''creates a new pair of username and password for each user(each line is
a user)'''
print(login_info)


print(lines)
print(login_info)

'''prompts user for their username and password'''
prompt_username = input("Please enter username: ")
prompt_password = input("Please input password: ")


The problem is in the following method(it does not work):

def login(username, password):
'''if username exists and the inputed strings match one of the key-value
pairs, login is successful'''

if username in login_info:
if password == info["password"]:
print("LOGIN SUCCESSFUL")
else:
print("Sorry, password does not exist.")
else:
print("Sorry this username or password does not exist.")

login(prompt_username, prompt_password)


How do I effectively check if the user inputs for username and password match any of the dictionary pairs to simulate a login?

The following is the users.json file.

users.json

File: users.json

users.json

"first": "Gilberto", "last": "Robles", "username": "girobles1", "password": "1234", "location": "San Diego", "interests": [["eat", "sleep", "code", "repeat"]]
"first": "Gilberto", "last": "Robles", "username": "girobles2", "password": "12345", "location": "San Diego", "interests": [["eat", "sleep", "code"]]


1 Answer
1

It looks like you're just calling the wrong object to check if the password is correct

if password == info["password"]:


should be

if password == login_info[username]:


Follow-up question about number of attempts:

I rewrote your function to return the status of the username and password accuracy:

def login(username, password):
'''if username exists and the inputed strings match one of the key-value
pairs, login is successful returns (Username Correct, Password Correct)'''

if username in login_info:
if password == login_info[username]:
print("LOGIN SUCCESSFUL")
return (True, True)
else:
print("Sorry, password does not exist.")
return (True, False)
else:
print("Sorry this username does not exist.")
return (False, False)

login(prompt_username, prompt_password)


Then added a loop to check the results and logic to handle them (This is untested, since I don't have your dictionary):

'''prompts user for their username and password'''
username_attempts = 3
password_attempts = 3

prompt_username = input("Please enter username: ")
prompt_password = input("Please input password: ")

username_guess = 1
password_guess = 1

while True: #Loops until broken
if username_guess > username_attempts:
print("Too many invalid usernames, goodbye")
#What do you want it to do if they fail?
break

if password_guess > password_attempts:
print("Too many invalid passwords, goodbye")
#What do you want it to do if they fail?
break

username_status, password_status = login(prompt_username, prompt_password)

if all([username_status, password_status]):
break

elif not username_status:
print("Invalid username, please try again")
prompt_username = input("Please enter username: ")
username_guess += 1

elif not password_status:
print("Invalid password, please try again")
prompt_password = input("Please input password: ")
password_guess += 1


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