A Simple Login System With Python & Tkinter

Devtekk

Published in

Satyam Kulkarni

5 min readMar 24, 2020

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

If you want to check only Source Code,

Github

Meanings of Terms we will be using throughout this Text

GUI — Graphical User Interface

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

Let’s Begin

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

First we will Install Required Libraries

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

app = MainWindow()
app.run()

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

Use following command to run python file

cd YourDirectory
python3 main.py

On Windows,

python main.py

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

Add a Login and register function in code

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 Databasedb = Database()
db.createTable()class Login:“””
 Class for Login
 @param username
 @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 username
 @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 PasswordTkinter — GUI librarydatabase — 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 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 Password.

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

Then arranges input data in tuple

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

After That, We check 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 them error

Except Block —

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

If We Not found them in 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 used to encrypt Password.

database.py

# Importing Important Librariesimport sqlite3
import bcryptclass 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 Insertig 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 0def 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.

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