refactor:flask

To refactor a monolithic Flask app using the application factory pattern, you create configurable app instances via a create_app function. This replaces global app instances, enabling better testing across multiple environments and separating configuration from initialization.

Moving business logic into a service layer separates concerns by pulling it out of fat Flask route handlers. This makes your code modular, improves reusability, and allows you to write focused unit tests around the services rather than the views.

The best way to organize Flask routes for maintainability is using Blueprints to group routes by domain. This Blueprint-based organization enforces modularization, reduces duplication, and makes scaling your application structure significantly easier.

Refactoring Flask apps with blueprints and services does not require external dependencies. It uses native Flask features like the application factory pattern and Blueprints, alongside standard Python typing hints and centralized error handling, to achieve a clean architecture.

You need to refactor your Flask project into a modular architecture when monolithic fat route handlers and global app instances become hard to maintain, test, and extend. Centralized error handling and a service layer solve these scalability issues.