Login and Registration Project in Flask using MySQL

Introduction

Creating a secure and functional login and registration system is an essential part of most web applications. In this blog, we'll build a simple Login and Registration Project in Flask using MySQL. This project includes user sign-up, login, session handling, and database connectivity — all vital components of any authentication system.

Prerequisites

To follow along, make sure you have the following installed:

• Python 3.x
• Flask
• MySQL Server
• MySQL Connector for Python

Step 1: Setting Up the Flask Project Structure

Start by creating a new directory for your project. Inside it, create the following files:

• app.py – main application file
• templates/ – folder containing HTML templates

Step 2: Install Required Packages

pip install flask
pip install mysql-connector-python

Step 3: Create the MySQL Database

Open your MySQL client and run the following commands to create a database and users table:

CREATE DATABASE flask_auth;
USE flask_auth;

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(100) NOT NULL,
    email VARCHAR(100) NOT NULL,
    password VARCHAR(100) NOT NULL
);

Step 4: Building the Flask App

from flask import Flask, render_template, request, redirect, session
import mysql.connector
import hashlib

app = Flask(__name__)
app.secret_key = 'your_secret_key'

conn = mysql.connector.connect(
    host='localhost',
    user='root',
    password='your_password',
    database='flask_auth'
)
cursor = conn.cursor()

@app.route('/')
def home():
    return render_template('login.html')

@app.route('/login', methods=['POST'])
def login():
    username = request.form['username']
    password = hashlib.sha256(request.form['password'].encode()).hexdigest()

    cursor.execute('SELECT * FROM users WHERE username=%s AND password=%s', (username, password))
    user = cursor.fetchone()

    if user:
        session['username'] = username
        return redirect('/dashboard')
    else:
        return 'Invalid credentials'

@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'POST':
        username = request.form['username']
        email = request.form['email']
        password = hashlib.sha256(request.form['password'].encode()).hexdigest()

        cursor.execute('INSERT INTO users (username, email, password) VALUES (%s, %s, %s)', 
                       (username, email, password))
        conn.commit()
        return redirect('/')
    return render_template('register.html')

@app.route('/dashboard')
def dashboard():
    if 'username' in session:
        return f'Welcome, {session["username"]}!'
    return redirect('/')

@app.route('/logout')
def logout():
    session.pop('username', None)
    return redirect('/')

if __name__ == '__main__':
    app.run(debug=True)

Step 5: Create HTML Templates

login.html

<form method="POST" action="/login">
  <input type="text" name="username" placeholder="Username" required><br>
  <input type="password" name="password" placeholder="Password" required><br>
  <button type="submit">Login</button>
  <p>Don't have an account? <a href="/register">Register here</a></p>
</form>

register.html

<form method="POST" action="/register">
  <input type="text" name="username" placeholder="Username" required><br>
  <input type="email" name="email" placeholder="Email" required><br>
  <input type="password" name="password" placeholder="Password" required><br>
  <button type="submit">Register</button>
</form>

Conclusion

You've now created a complete login and registration system in Flask using MySQL as the backend database. This project can serve as a strong foundation for more advanced applications involving role-based access, password hashing libraries like bcrypt, and user verification via email or tokens.