How to check username and password from a CSV. file

user_11149410 0
Viewed 1773

This is a school project that I'm trying to do, we have to create a program that asks the user if they have already had an account or not. If not they would have to enter a username, the program will have to check whether the username is already used or not.

import csv

with open('accountdatabase.csv')as csvfile:
    datareader = csv.reader(csvfile, delimiter=',')
    for row in datareader:
        print("###################################")

accountq = input("Do You Have An Account? Y/N:  ")

create = "pending"
while create != "completed":
    if accountq == "N":
        print("Please Create An Account:")
        print("")
        username = input("Please Enter Your Username: ")
        password = input("Please Enter A Password: ")
        if row[0] == username:
            print("Sorry Username Is Already Taken")
        else:
            print("Username Accepted")
            create = "completed"
            break

However, when writing the code, I came an across a logic error where whenever I add a new username it only checks the last username on the row, meaning the previous one is not being checked, this leads to the user being able to create a new account with the same usernames.

I still struggle calling in specific data from a specific Period and row no.

This is how I structure my data in the .csv file:

enter image description here

pandas csv python
3 Answers

Just keep a list of usernames when you parse the csv file:

import csv

usernames = []
with open('accountdatabase.csv')as csvfile:
    datareader = csv.reader(csvfile, delimiter=',')
    for row in datareader:
        usernames.append(row[0])

.....

if username in usernames:
    print("Sorry Username Is Already Taken")

This approach keeps the names in memory. This isn't exactly scalable, as it uses a ton of memory (O(N) space). You could also reread the csv and if you come across the username quit, but that would take O(N) time. Neither approach is really scalable. But either solution will work for this project. I'd recommend keeping them in memory since this is a small project, which is what the code above does.

user_34626710

Kindly rewrite the code :

-rest of the code-

for row in dataheader: if row[0] == username

-rest of the code-

Hope It works

user_87249530

You can do this easily using pandas library. The solution will be fast and smaller.

Note: you may have to install pandas if don't already have it.

pip install -U pandas

import pandas as pd

df = pd.read_csv('accountdatabase.csv', sep=',')

# Your trial username
trial_username = 'bob12'

# The username column is called 'username' in the CSV file
if trial_username in df['username'].tolist():
    print('Username NOT available.')
else:
    print('Username available.')

Let's try with some dummy data

We assume that once you read in the file using pandas.read_csv method, you have a dataframe df as follows. 

df = pd.DataFrame({'username': ['bob12', 'rickrock', 'jango.tango', 'captain.america'], 'password': None})
print(df)

Output: 

          username password
0            bob12     None
1         rickrock     None
2      jango.tango     None
3  captain.america     None

Now you want to test if a certain username is already taken or available. Here is the code for that. 

trial_username = 'bob12'

if trial_username in df['username'].tolist():
    print('Username NOT available.')
else:
    print('Username available.')

Result: 

Username NOT available.

Design

Check objective: SignIn or SignUp

If SignUp:
1. Check username availability.
1. If username is available: let user provide a password. 1. Save username and password to file.

If SignIn:
1. Check match for both username and password.
1. If match found: Credentials are VALID, else INVALID.

Check for SignUp Credentials

Assume this is your data. 

df = pd.DataFrame({'username': ['bob12', 'rickrock', 'jango.tango', 'captain.america'], 'password': None})
df['password'] = ['passw0rd']*df.shape[0]
print(df)

Dummy Data: 

          username  password
0            bob12  passw0rd
1         rickrock  passw0rd
2      jango.tango  passw0rd
3  captain.america  passw0rd

Check username and password validity for an existing user: 

user_username = 'bob12'
user_password = 'passw0rd'
valid_user = df['password'].loc[df['username'] == user_username] == user_password
print(valid_user)
user_84748940
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