title: How to monitor FastAPI application performance using Python agent
  - author: Jean-Baptiste Rocher
    author_link: https://hashnode.com/@jibrocher
    link: https://dev.indooroutdoor.io/series/fastapi-react-poll-app
    title: Building the Poll App From Django Tutorial With FastAPI And React
  - author: Silvan Melchior
    author_link: https://github.com/silvanmelchior

```

---

Si votre application n'a pas à communiquer avec une bibliothèque externe et pas à attendre de réponse, utilisez `async def`.

---

Si vous ne savez pas, utilisez seulement `def` comme vous le feriez habituellement.

---

**Note** : vous pouvez mélanger `def` et `async def` dans vos *fonctions de chemin* autant que nécessaire, **FastAPI** saura faire ce qu'il faut avec.

### Internal

* 🔧 Update sponsors, remove Flint. PR [#10349](https://github.com/tiangolo/fastapi/pull/10349) by [@tiangolo](https://github.com/tiangolo).
* 🔧 Rename label "awaiting review" to "awaiting-review" to simplify search queries. PR [#10343](https://github.com/tiangolo/fastapi/pull/10343) by [@tiangolo](https://github.com/tiangolo).

```

</div>

... qui comprend également `uvicorn`, que vous pouvez utiliser comme serveur pour exécuter votre code.

!!! note
    Vous pouvez également l'installer pièce par pièce.

    C'est ce que vous feriez probablement une fois que vous voudrez déployer votre application en production :

    ```
    pip install fastapi
    ```

    Installez également `uvicorn` pour qu'il fonctionne comme serveur :

    ```

Used by FastAPI / Starlette:

* <a href="https://www.uvicorn.org" target="_blank"><code>uvicorn</code></a> - for the server that loads and serves your application.
* <a href="https://github.com/ijl/orjson" target="_blank"><code>orjson</code></a> - Required if you want to use `ORJSONResponse`.

```

...that we used to make our requests with the `TestClient`.

!!! tip
    Note that we're using async/await with the new `AsyncClient` - the request is asynchronous.

!!! warning

### Make Peewee async-compatible `PeeweeConnectionState`

Used by FastAPI / Starlette:

* <a href="https://www.uvicorn.org" target="_blank"><code>uvicorn</code></a> - for the server that loads and serves your application.
* <a href="https://github.com/ijl/orjson" target="_blank"><code>orjson</code></a> - Required if you want to use `ORJSONResponse`.

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

    ```

As in this case (without using `Annotated`) we have to replace the default value `None` in the function with `Query()`, we now need to set the default value with the parameter `Query(default=None)`, it serves the same purpose of defining that default value (at least for FastAPI).

So:

```Python
q: Union[str, None] = Query(default=None)
```