Flask Authentication App Tutorial

This readme will guide you through setting up a basic Flask application with user authentication. We'll cover important concepts about Flask, templates, and SQL.

Step 1: Set up the environment

1. Install MySQL:

   brew install mysql
   brew services start mysql
   mysql_secure_installation
   

2. Create a virtual environment and activate it:

   python -m venv venv
   source venv/bin/activate
   

3. Install required packages:

   pip install -r requirements.txt
   

Step 2: Set up the database

1. Log in to MySQL:

   mysql -u root -p
   

2. Create the database and user:

   CREATE DATABASE flask_app_db;
   USE flask_app_db;
   CREATE USER 'flask_user'@'localhost' IDENTIFIED BY '1234';
   GRANT ALL PRIVILEGES ON flask_app_db.* TO 'flask_user'@'localhost';
   FLUSH PRIVILEGES;

Step 3: Understanding the Flask Application Structure

Our Flask app consists of several files:

1. main.py: The core of our Flask application
2. Templates:
   • base.html: The base template that other templates extend
   • home.html: The home page
   • login.html: The login page
   • register.html: The registration page
   • dashboard.html: The user dashboard

Key Concepts:

• Flask: A micro web framework for Python
• Jinja2 Templates: Flask's templating engine for dynamic HTML
• SQLAlchemy: An ORM (Object-Relational Mapping) for database operations
• Flask-SQLAlchemy: Flask extension for easy SQLAlchemy integration
• Werkzeug: Provides security features like password hashing

Step 4: Exploring the Code

main.py

This file sets up the Flask application, defines routes, and handles user authentication:

• We use Flask-SQLAlchemy to interact with our MySQL database
• The User model defines our database schema
• Routes are defined for home, register, login, dashboard, and logout
• We use werkzeug.security for password hashing

Templates

• base.html: Contains the basic structure of our HTML, including navigation
• home.html, login.html, register.html: Extend base.html and provide specific content
• dashboard.html: Shows user-specific information and allows attribute updates

Important Flask Concepts

1. Routing: @app.route() decorator maps URLs to functions
2. Request Handling: request.method and request.form for form data
3. Sessions: session object for maintaining user state
4. Flash Messages: flash() for user feedback
5. Redirects: redirect() and url_for() for navigation

Step 5: Running the Application

1. Ensure your virtual environment is activated
2. Run the Flask application:

   python flask_app.py
   

3. Open a web browser and navigate to http://localhost:5000