How do I search a SQL List inside of python to check if the username matches a user input?-CodePudding

So I am making a login page, and I need to compare the username of an SQL list to the user input. I will also use the answer for the password. This is what I have tried and it returns false.

list_of_users = [('[email protected]', 'qwerty'), ('jeremy', '123')]

for i in list_of_users:
    if i == '[email protected]':
        print("True")
    else:
        print("False")

The list_of_users is there to simulate what the SQL gives when you do cursor.fetchall() on an SQL database. Any input would be appriciated!

CodePudding user response：

Because the elements of your list are tuples of two elements. So each element has two in turn. See the definition in the official documentation of Data Structures - Tuples and Sequences.

If you wanted to fix your code, you would then simply add a second element to the for loop:

list_of_users = [('[email protected]', 'qwerty'), ('jeremy', '123')]

for email, pwd in list_of_users:
    if email == '[email protected]':
        print("True")
    else:
        print("False")

But this approach has a fundamental flaw for your use case. You want to print N times 'false'? Just iterate until the mail is found and stop.

This is an example toy code:

list_of_users = [('[email protected]', 'qwerty'), ('jeremy', '123')]


def login(email: str, pwd: str, list_of_users: [()]) -> bool:
    for db_email, db_pwd in list_of_users:
         if (email == db_email) and (pwd == db_pwd):
             return True
    return False


print(login('jeremy', '123', list_of_users))  # True
print(login('jeremy', '456', list_of_users))  # False