It will be added to the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        deprecated: Annotated[
            Optional[bool],
            Doc(
                """
                Mark this *path operation* as deprecated.

                It will be added to the generated OpenAPI (e.g. visible at `/docs`).

Before OpenAPI 3.1.0, OpenAPI used an older and modified version of **JSON Schema**.

JSON Schema didn't have `examples`, so OpenAPI added it's own `example` field to its own modified version.

OpenAPI also added `example` and `examples` fields to other parts of the specification:

                It will be added to the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        deprecated: Annotated[
            Optional[bool],
            Doc(
                """
                Mark this *path operation* as deprecated.

                It will be added to the generated OpenAPI (e.g. visible at `/docs`).

```

Here, the `shutdown` event handler function will write a text line `"Application shutdown"` to a file `log.txt`.

!!! info
    In the `open()` function, the `mode="a"` means "append", so, the line will be added after whatever is on that file, without overwriting the previous contents.

!!! tip
    Notice that in this case we are using a standard Python `open()` function that interacts with a file.

In that case, you can disable this feature in **FastAPI**, with the parameter `separate_input_output_schemas=False`.

!!! info
    Support for `separate_input_output_schemas` was added in FastAPI `0.102.0`. 🤓

=== "Python 3.10+"

    ```Python hl_lines="10"
    {!> ../../../docs_src/separate_openapi_schemas/tutorial002_py310.py!}
    ```

=== "Python 3.9+"

def use_route_names_as_operation_ids(app: FastAPI) -> None:
    """
    Simplify operation IDs so that generated API clients have simpler function
    names.

    Should be called only after all routes have been added.
    """
    for route in app.routes:
        if isinstance(route, APIRoute):
            route.operation_id = route.name  # in this case, 'read_items'

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="3"
    {!> ../../../docs_src/path_params_numeric_validations/tutorial001.py!}
    ```

!!! info
    FastAPI added support for `Annotated` (and started recommending it) in version 0.95.0.

    If you have an older version, you would get errors when trying to use `Annotated`.

    And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

## Custom Headers

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

    * Although it's probably not very problematic here with the way `SQLAlchemy` works.
    * But if you added more code to the middleware that had a lot of <abbr title="input and output">I/O</abbr> waiting, it could then be problematic.
* A middleware is run for *every* request.
    * So, a connection will be created for every request.

@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```

The server should reload automatically (because you added `--reload` to the `uvicorn` command above).

### Interactive API docs upgrade

Now go to <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.