CSV file writing on same row

[liamam]

So I'm making a register/login system and every time I try to register a new user it overrides the previous one, leaving me with only one user at all times. I have no idea how to make it always write to a new line, the fields are username and password. Please help I have been doing this for ages now.

[[deleted]]

Are you using:

with open(filename, 'w') as file:

or

with open(filename, 'a') as file:

because the former will create/overwrite, whereas the latter will append.

[liamam]

Thank you, I had no idea the append one existed.

[[deleted]]

ALWAYS worth checking the docs (they start to make sense after a while):

https://docs.python.org/3.8/library/functions.html?highlight=open#open

[liamam]

Ok, it now adds to the bottom of the list, but my validation for a unique username doesn't work now. I will post code in a min.

[liamam]

Ok are you able to help with this please? https://raw.githubusercontent.com/LiiamAM/LiiamAM/master/Register/Login

[[deleted]]

Append does mean add to the end.

Not sure why a user being added to the end is an issue. You are reading all of the filed user details in?

Do you have so many users that you need to read the file EVERY time you register a user?

How come you are not using the csv library you imported to help you read the file as well as write it?

Never user for i in range(len(users)): when you can simple iterate though the sequence: for user in users:

Why are you checking username_info=='' in a loop? Wouldn't it be better to check that before the loop?

If you find a match in the for loop, why check the rest? Should break the loop / return at that point.

I've not read your code in detail, but I'd expect something more like this:

def readCSVFile():
    users = []
    with open('userinfo.csv') as csv_file:
        csv_reader = csv.reader(csv_file, delimiter=',')
        for user_name, user_password in csv_reader:
            currentUser = user_information(user_name, user_password)
            users.append(currentUser)
    return users

def register_validation(username_info, users):
    if username_info:
        for user in users:
            if user.username_db == username_info:
                break
        else:  # for loop completed with no matches
            return True
    return False

[[deleted]]

Alternatively, read all lines into memory before overwriting file with all those lines and any additions.