What is Flask?

Flask is a lightweight Web framework written in Python. Flask started out as an April fool's joke that became a highly popular underdog in the Python web framework world. It is now one of the most widely used Python web frameworks for start-ups, and is becoming commonly accepted as the perfect tool for quick and simple solutions in most businesses. At its core, it provides a set of powerful libraries for handling the most common web development tasks, such as:

• URL routing that makes it easy to map URLs to your code
• Template rendering with Jinja2, one of the most powerful Python template engines
• Session management and securing cookies
• HTTP request parsing and flexible response handling
• Interactive web-based debugger
• Easy-to-use, flexible application configuration management

This book will teach you how to use these tools through practical, real-world examples. We will also discuss commonly used third-party libraries for things that are not included in Flask, such as database access and form validation. By the end of this book you will be ready to tackle your next big project with Flask.

With great freedom comes great responsibility

As the documentation states, Flask is fun, but it can also be challenging, especially when you are building a large application. Unlike other popular Python web frameworks, such as Django, Flask does not enforce ways of structuring your modules or your code. If you have experience with other web frameworks, you may be surprised how writing applications in Flask feels like writing Python as opposed to the framework boilerplate.

This book will teach you to use Flask to write clean, expressive applications. As you progress through this book, you will not only become a proficient Flask developer but you will also become a stronger Python developer.