Flask Course

Lesson 1 • Python Environment and Virtual Environments

Configure Python, pip, and isolated virtual environments for Flask projects. Proper isolation prevents dependency conflicts across projects.

Lesson 2 • Configuration Management

Load and switch between development, testing, and production configs. Externalized configuration keeps secrets out of source code.

Lesson 3 • Your First Flask Application

Write and run a minimal Flask app to understand the application factory pattern. Students trace a request from browser to Python function and back.

Lesson 4 • Installing and Configuring Flask

Install Flask and verify the installation with a minimal app. This establishes the baseline toolchain for all subsequent chapters.

Lesson 1 • Route Basics and HTTP Methods

Define routes with the @app.route decorator and restrict them to specific HTTP methods. This connects URL patterns to view logic.

Lesson 2 • Blueprints for Route Organization

Group related routes into Blueprints to modularize large applications. Blueprints are the foundation of scalable Flask architecture.

Lesson 3 • URL Building with url_for

Generate URLs from endpoint names instead of hardcoding strings. url_for keeps links consistent when routes change.

Lesson 4 • Dynamic URL Parameters

Capture variable segments in URLs and convert them to typed Python values. Dynamic routes enable resource-based URL design.

Lesson 1 • Rendering Templates with render_template

Pass Python data to HTML files using render_template and Jinja2 syntax. Templates separate presentation from business logic.

Lesson 2 • Template Inheritance and Blocks

Define a base layout template and extend it in child templates using block tags. Inheritance enforces a consistent site-wide structure.

Lesson 3 • Jinja2 Control Structures

Use if/else blocks and for loops inside templates to generate conditional and repeated HTML. Control structures eliminate redundant markup.

Lesson 4 • Macros, Includes, and Reusable Components

Encapsulate repeated HTML fragments as macros or included partials. Reusable components reduce duplication across many pages.

Lesson 1 • Validators and Error Messages

Apply built-in validators such as DataRequired and Email, and display error messages in templates. Validators enforce data integrity before processing.

Lesson 2 • File Uploads

Accept file uploads, validate file types, and save files securely to the server. Secure upload handling prevents path traversal and malicious file execution.

Lesson 3 • CSRF Protection

Enable and verify CSRF tokens in every form submission to prevent cross-site request forgery. CSRF protection is mandatory for any state-changing form.

Lesson 4 • Flask-WTF and WTForms Setup

Install Flask-WTF, configure a secret key, and define form classes with typed fields. Form classes centralize validation rules and field definitions.

Lesson 1 • Defining Models and Relationships

Create model classes that map to database tables and define one-to-many and many-to-many relationships. Models are the schema definition for the application.

Lesson 2 • Advanced Querying and Pagination

Write complex queries with joins, aggregates, and ordering, then paginate large result sets. Efficient queries reduce database load and improve response times.

Lesson 3 • Database Migrations with Flask-Migrate

Use Flask-Migrate to generate and apply schema migrations without data loss. Migrations enable safe, versioned schema evolution in production.

Lesson 4 • Setting Up Flask-SQLAlchemy

Install Flask-SQLAlchemy, configure the database URI, and initialize the db object. The db object is the central interface for all database operations.

Lesson 1 • Flask-Login Setup and User Loader

Install Flask-Login, configure the LoginManager, and implement the user_loader callback. The user_loader reconstructs the current user from the session on every request.

Lesson 2 • Password Hashing and User Model

Hash passwords with Werkzeug and store only hashed values in the database. Storing plaintext passwords is a critical security vulnerability.

Lesson 3 • Protecting Routes with login_required

Restrict access to views using the @login_required decorator and redirect unauthenticated users. Route protection enforces authorization at the view layer.

Lesson 4 • Role-Based Access Control

Assign roles to users and restrict views based on role membership. RBAC separates what different user types are permitted to do.

Lesson 1 • REST Principles and API Design

Apply REST constraints to design resource-oriented URL schemes and choose correct HTTP verbs. Good API design reduces client-side complexity.

Lesson 2 • Returning JSON Responses

Serialize Python objects to JSON using jsonify and set appropriate response headers. Consistent serialization ensures interoperability with API clients.

Lesson 3 • API Error Handling and Documentation

Return structured JSON error responses and document endpoints with docstrings or OpenAPI specs. Clear error messages and docs reduce integration friction.

Lesson 4 • API Authentication with Tokens

Protect API endpoints using token-based authentication with Flask-HTTPAuth or JWT. Stateless token auth is the standard for REST APIs.

Lesson 1 • Environment Variables and Secrets Management

Inject secrets and config via environment variables and use a .env file for local development. Externalizing secrets prevents credentials from entering version control.

Lesson 2 • Logging, Monitoring, and Error Tracking

Configure Python logging, structured log output, and integrate an error-tracking service. Observability enables fast diagnosis of production issues.

Lesson 3 • WSGI Servers and Reverse Proxies

Replace the development server with Gunicorn and place Nginx in front as a reverse proxy. Production WSGI servers handle concurrency the dev server cannot.

Lesson 4 • Test Fixtures and Coverage

Use pytest fixtures to set up and tear down test state, and measure code coverage with pytest-cov. Coverage metrics reveal untested code paths.