Why doesn't my script find the correct dictionary value?

Question

I have been writing this 'employee login' however, I can't get the two independent events to rely on each other.

It will look up the username just fine, but how can I get it to look up the subsequent password and not just any password in the dictionary?

requested_name = [input('Name : ').title()]
req_password = [int(input('Password: '))]

dic = {'John':123,'Mike':32}
auth = {'Admin': 142}

for requested_name in requested_name:
    if requested_name in dic.keys():
        print (f'Hello {requested_name}')

    elif requested_name in auth.keys():
        print('Hello Admin, Take Control')
    else:
        print ('Wrong Username')
        break
    
    for req_password in req_password:
        if req_password in dic.values():
             print('Access Granted')
        else:
            print('Access Denied')

Carson · Answer 1 · 2021-03-10T15:02:33.960

You can use a python dictionary to lookup a value by names. To do this, just do dictionary.get(key), where dictionary is your dictionary variable and key is the thing you want to lookup. From your example: dic.get('John') would return 123, and dic.get('Adam') doesn't return anything.

Checkout this modified example to see. Also a quick side note, its generally bad practice to name both variables in a for loop the same thing. You also need to decide if you're looking for the password in the auth dictionary, or in the regular users dictionary. In my example I checked both.

if requested_name in dic.keys():
    print (f'Hello {requested_name}')

elif requested_name in auth.keys():
    print('Hello Admin, Take Control')
else:
    print ('Wrong Username')
    break
    
for pwd in req_password:
    if pwd == dic.get(request_name):
        print('Access Granted')
    elif pwd == auth.get(request_name):
        print('Admin Access Granted')
    else:
        print('Access Denied')

As a note aside from your original question, there's some things you can do to make the input code a little cleaner. At the start, when you get your input, you do:

requested_name = [input('Name : ').title()]
req_password = [int(input('Password: '))]

The [] Around these are making requested_name be a list of length one, instead of just the variable. Think about x = 3 and how that's different to x = [3]. The second one make a list with three inside.

I went ahead and modified your code a little bit:

req_name = input('Name : ').title()
req_password = int(input('Password: '))

dic = {'John':123,'Mike':32}
auth = {'Admin': 142}

if req_name in dic.keys():
    # If we're in this block, it means this might be a regular user
    if req_password == dic.get(req_name):
        # Regular username, with correct password
        print(f'Hello {req_name}')
        print('Access Granted')
    else:
        # Regular username, but incorrect password
        print(f'Sorry {req_name}, Access Denied')
elif req_name in auth.keys():
    # If we're in this block, it means this might be an admin
    if req_password == auth.get(req_name):
        # Auth username with correct password
        print(f'Hello {req_name} take control')
        print('Access Granted')
    else:
        # Auth username with incorrect password
        print(f'Sorry {req_name}, Access Denied')
else:
    print('Wrong Username')

Notice how since we changed those first two lines, we don't need those for statements anymore. Also, since we want to use different lists for checking the password, depending on which the username is in, we can put the password checking code in with the username checking code.

Thank you, this is clearly.. I appreciate the explanation.. – nDox Mar 11 '21 at 09:12 — nDox, Mar 11 '21 at 09:12

score 1 · Answer 2 · answered Mar 10 '21 at 15:34

Other people already had good answers, here's another way to do it:

requested_name = input('Name : ').title()
req_password = int(input('Password: '))

dic = {'John':123,'Mike':32}
auth = {'Admin': 142}


if requested_name in dic.keys():
    print(f'Hello {requested_name}')
    if req_password == dic[requested_name]:
        print('Access Granted')
    else:
        print('Access Denied')

elif requested_name in auth.keys():
    if req_password == auth[requested_name]:
        print('Hello Admin, Take Control')
    else:
        print('Access Denied')
    
else:
     print('Wrong Username')

score 0 · Answer 3 · edited Mar 10 '21 at 15:10

You can iterate two lists in one go using zip.

For each username, check in the corresponding dict and if there is a match, store the corresponding variable.

After that, you can check the password entered and stored password in above steps to validate input.

See code below,

requested_name = [input('Name : ').title()]
req_password = [int(input('Password: '))]

dic = {'John': 123, 'Mike': 32}
auth = {'Admin': 142}


for req_name, req_pass in zip(requested_name, req_password):
    password = None
    if req_name in dic:
        print(f"Hello {req_name}")
        password = dic[req_name]
    elif req_name in auth:
        print("Hello Admin, Take Control")
        password = auth[req_name]
    else:
        print("Wrong Username")
        break

    if req_pass == password:
        print("Access Granted.!")
    else:
        print("Access Denied.!")

I noticed that in your code you are iterating the list like this,

for requested_name in requested_name:

This is not a best practice. Your list will be lost and you can't reuse in any other code block that may come later.

Why doesn't my script find the correct dictionary value?

3 Answers3