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We can also use this same approach to access the request body in an exception handler.

All we need to do is handle the request inside a `try`/`except` block:

```Python hl_lines="13  15"
{!../../../docs_src/custom_request_and_route/tutorial002.py!}
```

```Python
async def do_something():
    try:
        yield something
    finally:
        some_cleanup()
```

...that way the `finally` block is run regardless of any exception that might happen.

### Features

```Python
async with lifespan(app):
    await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

    {!> ../../../docs_src/sql_databases/sql_app/main.py!}
    ```

!!! info
    We put the creation of the `SessionLocal()` and handling of the requests in a `try` block.

    And then we close it in the `finally` block.

    This way we make sure the database session is always closed after the request. Even if there was an exception while processing the request.

```

!!! tip
    You can use `async` or regular functions.

    **FastAPI** will do the right thing with each, the same as with normal dependencies.

## A dependency with `yield` and `try`

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

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        <img class="sponsor-image" src="/img/sponsors/cryptapi-banner.svg" />
      </a>
    </div>
    <div class="item">

    Sie können `async`hrone oder reguläre Funktionen verwenden.

    **FastAPI** wird bei jeder das Richtige tun, so wie auch bei normalen Abhängigkeiten.

## Eine Abhängigkeit mit `yield` und `try`.

Wenn Sie einen `try`-Block in einer Abhängigkeit mit `yield` verwenden, empfangen Sie alle Exceptions, die bei Verwendung der Abhängigkeit geworfen wurden.

{!../../../docs_src/custom_response/tutorial008.py!}
```

1. This is the generator function. It's a "generator function" because it contains `yield` statements inside.
2. By using a `with` block, we make sure that the file-like object is closed after the generator function is done. So, after it finishes sending the response.

### Path operation functions

When you declare a *path operation function* with normal `def` instead of `async def`, it is run in an external threadpool that is then awaited, instead of being called directly (as it would block the server).