CODEWITHSUNDEEP
pythonvalidation
user3010402
user3010402

Reputation: 43

validating a username and passwords

I've asked a few questions about this code and luckily I'm almost finished but I have one final problem.

These are my functions: def valid_username(username): if not username.isalnum(): reason = ('username can only contain alpha numeric numbers') return '', reason

numupper =0
for c in username:
    if c.isupper():
        numupper = numupper + 1

if numupper <= 0:
    reason=('username must contain at least one uppercase character')
    return '',reason

numlower =0
for c in username:
    if c.islower():
        numlower = numlower + 1

if numlower <= 0:
    reason=('username must contain at least one lowercase character')
    return '', reason

    if len(username)<8:
        reason = ('username must be greater than 8 characters')
        return '',reason

numdigit=0
for c in username:
    if c.isdigit():
        numdigit = numdigit + 1

if numdigit <= 0:
    reason= ('username must contain at least one number')
    return '',reason

else:
    return username, ''

def valid_password(password): if not password.isalnum(): pwreason = ('password can only contain alpha numeric numbers') return '', pwreason

numupper =0
for c in password:
    if c.isupper():
        numupper = numupper + 1

if numupper <= 0:
    pwreason=('password must contain at least one uppercase character')
    return '',pwreason

numlower =0
for c in password:
    if c.islower():
        numlower = numlower + 1

if numlower <= 0:
    pwreason=('password must contain at least one lowercase character')
    return '', pwreason

    if len(password)<8:
        pwreason = ('password must be greater than 8 characters')
        return '',pwreason

numdigit=0
for c in password:
    if c.isdigit():
        numdigit = numdigit + 1

if numdigit <= 0:
    pwreason= ('password must contain at least one number')
    return '',pwreason

if username in password:
    print('username cannot be used as part of your password')

else:
    return password, ''

The username one works perfectly and the password one does too to an extent. This is my program:

import uservalidation

# get a username from the user
username = input("Username: ")

# validate username
result, reason = uservalidation.valid_username(username)

# if it isn't valid we should tell them why
if not(result):
     print (reason)

# otherwise the username is good - ask them for a password
# get a password from the user
password = input("Password: ")

# determine if the password is valid
pwresult, pwreason = uservalidation.valid_password(password)

# if the password isn't valid we should tell them why
if not(pwresult):
     print (pwreason)
else:
    print ("Username and Password combination is valid!")

The only part that doesn't seem to work is when I check to see if the password contains the username, the error I'm receiving states that username isn't a global variable but I thought it was since I ask the user to input it in the program outside of both functions. Thanks!

Upvotes: 0

Views: 8355

Answers (2)

Doobeh
Doobeh

Reputation: 9460

You seem to have gotten confused with the try and except clause. What you're probably aiming for is something like this, which avoids using exceptions altogether.

def valid_username(username):
    if not username.isalpha():
        reason = 'Username can only contain alpha characters'
        return reason

    if not any(x.isupper() for x in username):
        reason = 'Username must contain at least one uppercase character'
        return reason

    return "Username is good!"

print valid_username('FrankWorks')
print valid_username('frankfails')

Or using exceptions you could do:

def valid_username_using_exceptions(foo):
    if not foo.isalpha():
        raise ValueError('Username can only contain alpha characters')
    return True

    #.. Other validations functions... etc


failing_username = 'this_will_raise_an_exception_***'
try:
    if valid_username_using_exceptions(failing_username):
        print 'All good'
except ValueError, e:
    print "Failed!", e

Upvotes: 0

korylprince
korylprince

Reputation: 3009

except is used in the try...except statement. You haven't added a try clause to your code. It would seem from your code that you don't really understand how to handle exceptions properly.

This would be a good introduction for you.

Upvotes: 3

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