)

_T = TypeVar("_T")


@asynccontextmanager
async def contextmanager_in_threadpool(
    cm: ContextManager[_T],
) -> AsyncGenerator[_T, None]:
    # blocking __exit__ from running waiting on a free thread
    # can create race conditions/deadlocks if the context manager itself
    # has its own internal pool (e.g. a database connection pool)

    Define it as a *path operation function* (or dependency) parameter.

    If you are using a regular `def` function, you can use the `upload_file.file`
    attribute to access the raw standard Python file (blocking, not async), useful and
    needed for non-async code.

    Read more about it in the
    [FastAPI docs for Request Files](https://fastapi.tiangolo.com/tutorial/request-files/).

    ## Example

    ```python

!!! warning
    Você pode provavelmente pular isso.

    Esses são detalhes muito técnicos de como **FastAPI** funciona por baixo do capô.

    Se você tem algum conhecimento técnico (corrotinas, threads, blocking etc) e está curioso sobre como o FastAPI controla o `async def` vs normal `def`, vá em frente.

### Funções de operação de rota

It is connecting to the database and storing the connection data in an internal variable that is independent for each request (using the `contextvars` tricks from above).

Because the database connection is potentially I/O blocking, this dependency is created with a normal `def` function.

And then, in each *path operation function* that needs to access the database we add it as a dependency.

!!! warning
    You can probably skip this.

    These are very technical details of how **FastAPI** works underneath.

    If you have quite some technical knowledge (coroutines, threads, blocking, etc.) and are curious about how FastAPI handles `async def` vs normal `def`, go ahead.

### Path operation functions

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

### <a href="https://github.com/encode/apistar" class="external-link" target="_blank">APIStar</a> (<= 0.5)

Right before deciding to build **FastAPI** I found **APIStar** server. It had almost everything I was looking for and had a great design.

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

!!! warning
    Muhtemelen burayı atlayabilirsiniz.

    Bunlar, **FastAPI**'nin altta nasıl çalıştığına dair çok teknik ayrıntılardır.

    Biraz teknik bilginiz varsa (co-routines, threads, blocking, vb)ve FastAPI'nin "async def" ile normal "def" arasındaki farkı nasıl işlediğini merak ediyorsanız, devam edin.

### Path fonksiyonu

    Dies sind sehr technische Details darüber, wie **FastAPI** unter der Haube funktioniert.

    Wenn Sie über gute technische Kenntnisse verfügen (Coroutinen, Threads, Blocking, usw.) und neugierig sind, wie FastAPI mit `async def`s im Vergleich zu normalen `def`s umgeht, fahren Sie fort.

### Pfadoperation-Funktionen