A Simple Login System With Python & Tkinter

Satyam Kulkarni — Sun, 11 Oct 2020 20:51:50 +0000

Hi Everyone, This Article is Explaining all about How to Build a Simple Login System with Python and Tkinter

Photo by Maxwell Nelson on Unsplash

If you want to check only Source Code,

Github

Meanings of Terms we will be using throughout this Text

Photo by Pisit Heng on Unsplash

GUI — Graphical User Interface

It is the Screen that will appear with Interactive Text, Button, etc.

Let’s Begin

Photo by Kyle Glenn on Unsplash

This Login System is made with Tkinter, a Python In-Built Library for Building Cross-Platform GUI’s.

It also uses some other Libraries like Bcrypt, for Encrypting Password and Sqlite3, a Python In-Built Library for Interacting with SQlite3 Databases.

Fasten Your SeatBelt Programmer

Photo by Fabian Grohs on Unsplash

First we will Install Required Libraries

Tkinter — It is Pre Installed with Python, but for sometimes it does not come. It happened to me.

sudo apt-get install python-tk

Now, Coming Towards Bcrypt and SQlite3.

pip install bcrypt

SQlite3 Comes Pre Installed

Structuring our main.py

main.py is Main Entry Point for our App.

We will be Using OOP Methodology to program our Login System

Here,

*Line 1, *Import all functions from Tkinter Library

Line 3, Defines a Class called MainWindow for our Program

Line 4, It is init() Special Method for Classes which help to define local variables for Classes

In init() method, We define the app and make it an instance of Tk() class of Tkinter

And other stuff is,

Title — It is used to assign a Title to our Main Window

Geometry — It is a String used to define the Height and Width of our GUI

Label — It is used to print text on Screen or GUI

Button — It is used to create a Button

Add these 2 lines below the above code to run it...

app = MainWindow()
app.run()

And then go to terminal, and cd into that directory.

Use the following command to run python file

cd YourDirectory
python3 main.py

On Windows,

python main.py

This code will produce an error, as some things need to be changed,

Add a Login and register function in code

The Code Should Look Something like this,

from tkinter import *
from login import Login, Register

class MainWindow:
 def __init__(self):
 self.app = Tk()
 self.app.title(“Login with Python”)
 self.app.geometry(“300x250”)
 self.label = Label(self.app, text=”Welcome To App”)
 self.label.place(x=95, y=40)
 self.login = Button(self.app, text=”Login”,
 pady=5, padx=30, command=login)
 self.login.place(x=100, y=100)
 self.register = Button(self.app, text=”Register”,
 pady=5, padx=20, command=register)
 self.register.place(x=100, y=150)

def run(self):
 self.app.mainloop()

def login():
 loginTk = Login()
 loginTk.run()

def register():
 registerTk = Register()
 registerTk.run()

app = MainWindow()
app.run()

Now, You need to create a file named “login.py” to store Login and Register Class.

login.py

from tkinter import *
from tkinter import messagebox
import bcrypt
from database import Database

db = Database()
db.createTable()

class Login:

“””
 Class for Login
 [@param](http://twitter.com/param) username
 [@param](http://twitter.com/param) password
 “””

def __init__(self):
 “””
 Class Init Method for GUI
 :params — loginWindow, label, username
 “””

# Variables for Tkinter
 self.loginWindow = Tk()
 self.loginWindow.title(“Login with Python”)
 self.loginWindow.geometry(“300x250”)
 self.label = Label(self.loginWindow, text=”Login”)
 self.label.place(x=95, y=40)

# Just Creepy Tkinter Stuff
 self.usernameS = StringVar()
 self.passwordS = StringVar()

self.usernameE = Entry(
 self.loginWindow, relief=FLAT, textvariable=self.usernameS)
 self.usernameE.place(x=70, y=80)
 self.passwordE = Entry(
 self.loginWindow, show=”*”, relief=FLAT, textvariable=self.passwordS)
 self.passwordE.place(x=70, y=120)

# Actual Variales
 self.username = self.usernameS.get()
 self.password = self.passwordS.get()

self.submit = Button(self.loginWindow, text=”Submit”,
 pady=5, padx=20, command=self.validate)
 self.submit.place(x=100, y=150)

def validate(self):
 data = (self.username,)
 inputData = (self.username, self.password,)
 try:
 if (db.validateData(data, inputData)):
 messagebox.showinfo(“Successful”, “Login Was Successful”)
 else:
 messagebox.showerror(“Error”, “Wrong Credentials”)
 except IndexError:
 messagebox.showerror(“Error”, “Wrong Credentials”)

def run(self):
 self.loginWindow.mainloop()

class Register:

“””
 Class for Register
 [@param](http://twitter.com/param) username
 [@param](http://twitter.com/param) password
 “””

def __init__(self):

self.registerWindow = Tk()
 self.registerWindow.title(“Register with Python”)
 self.registerWindow.geometry(“300x250”)
 self.label = Label(self.registerWindow, text=”Register”)
 self.label.place(x=95, y=40)

# Just Creepy Tkinter Stuff
 self.usernameS = StringVar()
 self.passwordS = StringVar()

self.usernameE = Entry(self.registerWindow,
 relief=FLAT, textvariable=self.usernameS)
 self.usernameE.place(x=70, y=80)
 self.passwordE = Entry(self.registerWindow, show=”*”,
 relief=FLAT, textvariable=self.passwordS)
 self.passwordE.place(x=70, y=120)
 self.submit = Button(self.registerWindow,
 text=”Submit”, pady=5, padx=20, command=self.add)
 self.submit.place(x=100, y=150)

# Actual Variales
 self.username = self.usernameS.get()
 self.password = self.passwordS.get()

self.salt = bcrypt.gensalt()
 self.hashed = bcrypt.hashpw(self.password.encode(), self.salt)

def run(self):
 self.registerWindow.mainloop()

def add(self):
 data = (self.username,)

result = db.searchData(data)

print(result)

if result != 0:
 data = (self.username, self.hashed)
 db.insertData(data)
 messagebox.showinfo(“Successful”, “Username Was Added”)
 else:
 messagebox.showwarning(“Warning”, “Username already Exists”)

Explaining Code

First of all, We Import Libraries —

Bcrypt — for Encrypting Password

Tkinter — GUI library

database — It is our python file which has some SQlite Code in it

Then, We create Instance of Database Class present inside database.py

And Then, call the method of that class — Which will create a Table for us

db = Database()
db.createTable()

We Defined Login Class, which will handle all Login related Stuff

Then we define Dunder Method or Special Method of Python

def __init__():

In that, we have some Tkinter related stuff.

Second Method of Login Class:

def validate():

This method will Validate Login and match the Password.

It arranges username — for finding the user in the database in a tuple

Then arranges input data in a tuple

def validate(self):
 data = (self.username,)
 inputData = (self.username, self.password,)

After That, We check to call a method from Database Class to ValidateData or check Data.

try:
 if (db.validateData(data, inputData)):
 messagebox.showinfo(“Successful”, “Login Was Successful”)
 else:
 messagebox.showerror(“Error”, “Wrong Credentials”)

If you look carefully, We Started a Try — Except Block.

We check if we have some return value and then show the user “They Have Successfully Logged In”

Else we show the error

Except Block —

except IndexError:
 messagebox.showerror(“Error”, “Wrong Credentials”)

If We Not found them in the Database, then SQLite will throw **IndexError, **which we can tackle easily...

After that, we defined a Register Class — Which will do the same but it adds it the to database and with

self.salt = bcrypt.gensalt()
self.hashed = bcrypt.hashpw(self.password.encode(), self.salt)

It is used to encrypt Password.

database.py

# Importing Important Libraries

import sqlite3
import bcrypt

class Database:
 ‘’’
 Database Class for sqlite3
 :params conn — sqlite3Connection
 :params curr — cursor
 ‘’’

def __init__(self):
 try:
 self.conn = sqlite3.connect(“test.db”)
 print(“Successfully Opened Database”)
 self.curr = self.conn.cursor()
 except:
 print(“Failed”)

def createTable(self):
 ‘’’
 Method for Creating Table in Database
 ‘’’

create_table = ‘’’
 CREATE TABLE IF NOT EXISTS cred(
 id Integer PRIMARY KEY AUTOINCREMENT,
 username TEXT NOT NULL,
 password TEXT NOT NULL
 );
 ‘’’

self.curr.execute(create_table)
 self.conn.commit()

def insertData(self, data):
 ‘’’
 Method for Inserting Data in Table in Database
 ‘’’

insert_data = “””
 INSERT INTO cred(username, password)
 VALUES(?, ?);
 “””
 self.curr.execute(insert_data, data)
 self.conn.commit()

def searchData(self, data):
 ‘’’
 Method for Searching Data in Table in Database
 ‘’’

search_data = ‘’’
 SELECT * FROM cred WHERE username = (?);
 ‘’’

self.curr.execute(search_data, data)

rows = self.curr.fetchall()
 if rows == []:
 return 1
 return 0

def validateData(self, data, inputData):
 ‘’’
 Method for Validating Data Table in Database
 ‘’’

print(data)
 print(inputData)

validate_data = “””
 SELECT * FROM cred WHERE username = (?);
 “””

self.curr.execute(validate_data, data)
 row = self.curr.fetchall()

if row[0][1] == inputData[0]:
 return row[0][2] == bcrypt.hashpw(inputData[1].encode(), row[0][2])

These are some bunch of SQL Commands executed with Python.

Thanks for Your Time.

Stay Home, Stay Safe

Satyam Kulkarni

DEV Community: Satyam Kulkarni