What is the Lifespan State on FastAPI?

When developing web applications with FastAPI, you may come across the concept of “lifespan state”. But what exactly does this mean?

In FastAPI, the “lifespan state” refers to the state of the application at different points in its lifecycle. This includes the startup, shutdown, and reload events that occur during the runtime of the application.

During the startup event, the application initializes and sets up any necessary resources, such as database connections or external services. This is the ideal time to perform any tasks that need to be completed before the application can start serving requests.

On the other hand, the shutdown event occurs when the application is about to stop running. This is where you can clean up any resources or perform any necessary cleanup tasks before the application shuts down entirely.

Additionally, FastAPI also supports the “reload” event, which occurs when the application is reloaded, typically during development when code changes are made and the server needs to be restarted. This event allows you to perform any necessary actions before the application is reloaded.

By understanding the lifespan state in FastAPI, you can effectively manage the startup, shutdown, and reload processes of your application, ensuring that it runs smoothly and efficiently.

Overall, the lifespan state in FastAPI provides a way to manage the application’s state at different points in its lifecycle, allowing for proper initialization, cleanup, and reload functionality.