You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version

The first thing you should do is to "pin" the version of **FastAPI** you are using to the specific latest version that you know works correctly for your application.

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001.py!}
    ```

!!! warning
    Notice that `Field` is imported directly from `pydantic`, not from `fastapi` as are all the rest (`Query`, `Path`, `Body`, etc).

## Declare model attributes

You can then use `Field` with model attributes:

=== "Python 3.10+"

    ```Python hl_lines="11-14"

```

## Create the new database session

First, we create a new database session with the new database.

We'll use an in-memory database that persists during the tests instead of the local file `sql_app.db`.

But the rest of the session code is more or less the same, we just copy it.

```Python hl_lines="8-13"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

!!! tip

<div style="text-align: right; margin-right: 10%;">Timothy Crosley - <strong><a href="https://www.hug.rest/" target="_blank">Hug</a> creator</strong> <a href="https://news.ycombinator.com/item?id=19455465" target="_blank"><small>(ref)</small></a></div>

---

"_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 [...]_"

<div style="text-align: right; margin-right: 10%;">Timothy Crosley - <strong><a href="https://www.hug.rest/" target="_blank">Hug</a> creator</strong> <a href="https://news.ycombinator.com/item?id=19455465" target="_blank"><small>(ref)</small></a></div>

---

"_Если вы хотите изучить какой-нибудь **современный фреймворк** для создания REST API, ознакомьтесь с **FastAPI** [...] Он быстрый, лёгкий и простой в изучении [...]_"

<div style="text-align: right; margin-right: 10%;">Timothy Crosley - <strong><a href="https://www.hug.rest/" target="_blank">Hug</a> creator</strong> <a href="https://news.ycombinator.com/item?id=19455465" target="_blank"><small>(ref)</small></a></div>

---

"_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 [...]_"

* **CORS** (_Cross Origin Resource Sharing_ - Compartilhamento de Recursos Entre Origens).
* _Worker_ **Celery** que pode importar e usar modelos e códigos do resto do _backend_ seletivamente.

<div style="text-align: right; margin-right: 10%;">Timothy Crosley - <strong><a href="https://www.hug.rest/" target="_blank">Hug</a> 作者</strong> <a href="https://news.ycombinator.com/item?id=19455465" target="_blank"><small>(ref)</small></a></div>

---

「_如果你正打算学习一个**现代框架**用来构建 REST API，来看下 **FastAPI** [...] 它快速、易用且易于学习 [...]_」

「_我们已经将 **API** 服务切换到了 **FastAPI** [...] 我认为你会喜欢它的 [...]_」

* **CORS** (partage des ressources entre origines multiples, ou *Cross Origin Resource Sharing*).
* *Worker* **Celery** pouvant importer et utiliser les modèles et le code du reste du backend.

* In code blocks within the Markdown document, translate comments (`# a comment`), but leave the rest unchanged.

* Do not change anything enclosed in "``" (inline code).

* In lines starting with `===` or `!!!`, translate only the ` "... Text ..."` part. Leave the rest unchanged.