Si vous avez de bonnes connaissances techniques (coroutines, threads, code bloquant, etc.) et êtes curieux de comment **FastAPI** gère `async def` versus le `def` classique, cette partie est faite pour vous.

### Fonctions de chemin

Mas antes disso, controlar código assíncrono era bem mais complexo e difícil.

Nas versões anteriores do Python, você poderia utilizar threads ou <a href="http://www.gevent.org/" class="external-link" target="_blank">Gevent</a>. Mas o código é um pouco mais complexo de entender, debugar, e pensar sobre.

    This was useful in older frameworks designed to have one single thread per request, no more, no less.

    Using this, each request would have its own database connection/session, which is the actual final goal.

But before that, handling asynchronous code was quite more complex and difficult.

In previous versions of Python, you could have used threads or <a href="https://www.gevent.org/" class="external-link" target="_blank">Gevent</a>. But the code is way more complex to understand, debug, and think about.

SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"
# SQLALCHEMY_DATABASE_URL = "postgresql://user:password@postgresserver/db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

    def __setattr__(self, name, value):
        self._state.get()[name] = value

    def __getattr__(self, name):
        return self._state.get()[name]


db = peewee.SqliteDatabase(DATABASE_NAME, check_same_thread=False)

```

#### 注意

参数:

```Python
connect_args={"check_same_thread": False}
```

...仅用于`SQLite`，在其他数据库不需要它。

!!! info "技术细节"

    默认情况下，SQLite 只允许一个线程与其通信，假设有多个线程的话，也只将处理一个独立的请求。

    这是为了防止意外地为不同的事物（不同的请求）共享相同的连接。

    但是在 FastAPI 中，普遍使用def函数，多个线程可以为同一个请求与数据库交互，所以我们需要使用`connect_args={"check_same_thread": False}`来让SQLite允许这样。

    此外，我们将确保每个请求都在依赖项中获得自己的数据库连接会话，因此不需要该默认机制。

Davor war der Umgang mit asynchronem Code jedoch deutlich komplexer und schwieriger.

In früheren Versionen von Python hätten Sie Threads oder <a href="https://www.gevent.org/" class="external-link" target="_blank">Gevent</a> verwenden können. Der Code ist jedoch viel komplexer zu verstehen, zu debuggen und nachzuvollziehen.

Pero antes de eso, manejar código asíncrono era bastante más complejo y difícil.

En versiones anteriores de Python, podrías haber utilizado <abbr title="En español: hilos.">threads</abbr> o <a href="https://www.gevent.org/" class="external-link" target="_blank">Gevent</a>. Pero el código es mucho más complejo de entender, depurar y desarrollar.

## Çok Teknik Detaylar

!!! 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