Python Bottle - checking if what the user has entered is in a database

Question

I'm making a 'shop' with customers, items and orders for my CS class task.

I am building onto it, so that it can be accessed via the web rather than a command line and I'm using Bottle.

I am trying to create a 'Create Account' page, but I want it so that there is an alert when the user enters a username that is already taken.

The username is in a SQLite3 database.

For the command line version:

I got a list of taken usernames using this:

store.curs.execute("SELECT username FROM customers")
validUsernames = [u[0] for u in store.curs.fetchall()]

and then I had something like this:

while True:
    username = str(input("USERNAME: "))
    if username not in validUsernames:
        store.insert_customer_data(firstname,lastname,address,username)
        print("Account created")
    else:
        print("Username taken, try again.")

So that the user had to enter a non-taken username.

(I do not need something to authenticate the passwords.)

Is there any way how to do this with Bottle?

Thanks.

Answer 1

I just did something simple, with a 'newaccount' page I put the form on there, and in the function for the 'POST' method I got the usernames like

store.curs.execute("SELECT username FROM customers")

and put it into a list using list comprehension:

validUsernames = [u[0] for u in store.c.fetchall()]

Got the info from the form using request.forms.get and then just used an if statement, if the username is not in validUsernames then it inserts the data into the database and takes the user to the login page. Else, it goes to another page with 'Username taken' and the user can click to go back to the main page.

I could shorten this with a 'popup' with 'Username Taken' and then redirecting back to the newaccount page after the user has clicked 'Okay', but I am not sure how to do this?

EDIT:: On the else (if the username is taken) I used redirect('newaccount?error=Username Taken') and got it using request.query.error and printed it in the newaccount page if there was an error.