on_event() — fastapi Function Reference

Architecture documentation for the on_event() function in applications.py from the fastapi codebase.

Function python FastAPI Applications calls 1

Entity Profile

FastAPI→ Applications→ on_event() — fastapi Function Reference

Dependency Diagram

graph TD
  dac05d36_d298_20ac_8313_653329a27887["on_event()"]
  587454b3_6db6_011f_9fa4_3e4e2e09b72d["FastAPI"]
  dac05d36_d298_20ac_8313_653329a27887 -->|defined in| 587454b3_6db6_011f_9fa4_3e4e2e09b72d
  a27c576c_fb92_8398_f37e_212c576404a2["on_event()"]
  dac05d36_d298_20ac_8313_653329a27887 -->|calls| a27c576c_fb92_8398_f37e_212c576404a2
  style dac05d36_d298_20ac_8313_653329a27887 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

fastapi/applications.py lines 4560–4579

    def on_event(
        self,
        event_type: Annotated[
            str,
            Doc(
                """
                The type of event. `startup` or `shutdown`.
                """
            ),
        ],
    ) -> Callable[[DecoratedCallable], DecoratedCallable]:
        """
        Add an event handler for the application.

        `on_event` is deprecated, use `lifespan` event handlers instead.

        Read more about it in the
        [FastAPI docs for Lifespan Events](https://fastapi.tiangolo.com/advanced/events/#alternative-events-deprecated).
        """
        return self.router.on_event(event_type)