{% endfor %}
{% endfor %}
{% endfor %}

## 🏗

⏪ 📂 🏗 ⏮️ ❔ `fastapi`:

<div class="github-topic-projects">

```

这里的变量 `app` 会是 `FastAPI` 类的一个「实例」。

这个实例将是创建你所有 API 的主要交互对象。

这个 `app` 同样在如下命令中被 `uvicorn` 所引用：

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

如果你像下面这样创建应用：

```Python hl_lines="3"
{!../../../docs_src/first_steps/tutorial002.py!}
```

Then you could disable OpenAPI (including the UI docs) by setting the environment variable `OPENAPI_URL` to the empty string, like:

<div class="termy">

```console
$ OPENAPI_URL= uvicorn main:app

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

Then if you go to the URLs at `/openapi.json`, `/docs`, or `/redoc` you will just get a `404 Not Found` error like:

## Install `python-jose`

We need to install `python-jose` to generate and verify the JWT tokens in Python:

<div class="termy">

```console
$ pip install "python-jose[cryptography]"

---> 100%
```

</div>

<a href="https://github.com/mpdavis/python-jose" class="external-link" target="_blank">Python-jose</a> requires a cryptographic backend as an extra.

a.announce-link:hover {
  color: var(--md-accent-fg-color);
}

.announce-wrapper {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  align-items: center;
}

.announce-wrapper div.item {
  display: none;
}

.announce-wrapper .sponsor-badge {
  display: block;
  position: absolute;
  top: -10px;
  right: 0;
  font-size: 0.5rem;
  color: #999;
  background-color: #666;

```

### Check the automatic API docs

Now, run `uvicorn` with the main app, if your file is `main.py`, it would be:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

And open the docs at <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

# First Steps

The simplest FastAPI file could look like this:

```Python
{!../../../docs_src/first_steps/tutorial001.py!}
```

Copy that to a file `main.py`.

Run the live server:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

{% endfor %}
{% endif %}

## 项目

GitHub 上最新的 `fastapi` 主题项目：

<div class="github-topic-projects">

## Instalação de dependências

Para instalar o `jinja2`, siga o código abaixo:

<div class="termy">

```console
$ pip install jinja2
```

</div>

## Usando `Jinja2Templates`

* Importe `Jinja2Templates`.
* Crie um `templates` que você possa reutilizar posteriormente.

{!../../../docs_src/sub_applications/tutorial001.py!}
```

### 查看文档

如果主文件是 `main.py`，则用以下 `uvicorn` 命令运行主应用：

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

查看文档 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs。</a>