Flask Routing and Views

Course overview

Uplatz provides this in-depth course on Flask: Build and Deploy Web Apps with Python. It is a self-paced course consisting of video tutorials. You will be awarded Course Completion Certificate at the end of the course.

What is Flask?

Flask is a lightweight, open-source web framework written in Python. It allows developers to build web applications quickly and with minimal code, making it a popular choice for beginners and professionals alike.

Flask is often called a “micro-framework” because it provides only the essential tools to get a web server up and running. It doesn’t include built-in features like database abstraction or form validation — but it’s highly extensible, so you can add what you need.

How Flask Works

Flask is a lightweight web framework in Python that enables developers to build web applications quickly and with great flexibility. At its core, Flask is designed to handle incoming web requests, process them through defined logic, and return appropriate responses to users, such as web pages or data.

When a user visits a website or interacts with an application built using Flask, their request is directed to the Flask application running on a server. Flask contains a routing system that determines which part of the application should handle a specific URL or request. Each URL is associated with a function that carries out the intended operation, whether it’s displaying a webpage, retrieving data from a database, or processing a form submission.

Once the appropriate function is triggered, Flask executes any necessary business logic. This may involve querying a database, applying calculations, or validating input. After processing, Flask prepares a response. This response could be a complete HTML page rendered using templates, or structured data like JSON, depending on what the application is designed to return.

Finally, Flask sends this response back to the client, usually a web browser or mobile app, completing the interaction. Throughout this process, Flask manages essential components such as request handling, response formatting, session management, and error handling. Its modular design allows developers to extend its capabilities easily by integrating additional tools or libraries, making Flask suitable for both simple projects and more complex applications that require scalability and customization.

Key Features of Flask

1. Lightweight and Minimalistic
   Flask provides the essentials for web development without enforcing a specific project structure or dependencies, giving developers full control.

2. Built-in Development Server
   It includes a simple server for testing and debugging during development.

3. Routing System
   Flask offers a powerful yet simple way to define how different URLs map to functions that handle them.

4. Template Engine (Jinja2)
   Flask uses Jinja2, a modern templating engine, to generate HTML pages dynamically with Python logic embedded.

5. Integrated Debugger
   Flask features a debugger that helps identify and resolve errors during development, including interactive stack traces.

6. Request and Response Handling
   It provides tools to access data from web requests (like form inputs or query parameters) and to structure responses (HTML, JSON, etc.).

7. Session Management
   Flask allows you to store user data across requests using secure cookies.

8. Extensible with Extensions
   There are many community-developed extensions that add features like form handling, authentication, database integration, and more.

9. RESTful Request Dispatching
   Flask makes it easy to build APIs by supporting RESTful patterns and response formatting.

10. Modular Design
    Flask encourages a modular approach to development, allowing applications to be split into reusable components.

11. Compatibility with WSGI
    Flask is built on the WSGI standard, making it compatible with most Python web servers and deployment tools.

12. Large Community and Documentation
    Flask has an active community and comprehensive documentation, making it easy to find support, tutorials, and third-party tools.