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

Question

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.

File: 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.

File: 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"]]}

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