CODEWITHSUNDEEP
pythonpython-3.x
Pearl
Pearl

Reputation: 11

Log In feature creates KeyError when username doesn't exist - Python

I am creating a game which begins with a log in feature

The user can 'Log in (A) or Create an account(B)'

My issue is if the user logs in with a username which doesn't exist I get a KeyError: "(whatever username they typed)"

Full Error shown

Expected Result: I would like the code to output 'User doesn't exist' if this happens.

The problem can be reproduced with this code and typing 'A' to log in and entering a random username which doesn't exist.

users = {} # Currently empty list called Users. Stores all log ins
global status
status = ""

def LogIn():#Function is called Log In. Can be called at any time.
    status = input("Log in (A) or Create an account(B) - Enter 'A' or 'B' ")   # asks for log in information
    status = status.upper()
    if status == "A":
        oldUser() #Already has an account
    elif status == "B":
        newUser() #Would like to make a new account
        return status #Moves on to the function named status

def newUser(): # Creating an account.
    CreateUsername = input("Create username: ") #Enter a what your username is

    if CreateUsername in users: # check if login name exists in the list
        print ("\n Username already exists!\n")
    else:
        createPassw = input("Create password: ")
        users[CreateUsername] = createPassw # add login and password
        print("\nUser created!\n")     

def oldUser():
    username = input("Enter username: ")
    passw = input("Enter password: ")

    # check if user exists and login matches password
    if passw == users[username]:
      print ("Login successful!\n")
      print('Game begins')
    else:
        print ("\nUser doesn't exist or wrong password!\n")

while status != "q":            
    status = LogIn()

Extra Info: more context of how the log in feature works. More Context

Upvotes: 0

Views: 350

Answers (3)

Pearl
Pearl

Reputation: 11

Fixed by altering

def oldUser():
    username = input("Enter username: ")
    passw = input("Enter password: ")

    # check if user exists and login matches password
    if username not in users:
      print ("Username doesn't exist")
      print('Game begins')
    elif passw == users[username]:
        print('Log In successful')
    else:
        print ("\nUser doesn't exist or wrong password!\n")

while status != "q":            
    status = LogIn()

Upvotes: 0

Benjamin Parsons
Benjamin Parsons

Reputation: 35

Look into using python's try and except. These exist to help us handle errors when they arise while customizing the way you handle those errors. So for your specific question, give this a shot:

def oldUser():
   username = input("Enter username: ")
   passw = input("Enter password: ")

# check if user exists and login matches password
   try:
     if passw == users[username]:
        print ("Login successful!\n")
        print('Game begins')
   except:
      print ("\nUser doesn't exist or wrong password!\n")

Upvotes: 0

JigglyThing
JigglyThing

Reputation: 81

You're getting an error because you're trying to access the users dictionary with a key that isn't in the dictionary. The key you're using is the username of the user. Therefore, when there isn't a user in the dictionary with that username you receive the KeyError

An alternative to using try and except would be to restructure your dictionary to be an array of user dictionaries, with each user dictionary containing the keys username and password

Upvotes: 1

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