假设要在*路径操作函数*中获取客户端 IP 地址和主机。

此时，需要直接访问请求。

```Python hl_lines="1  7-8"
{!../../docs_src/using_request_directly/tutorial001.py!}
```

把*路径操作函数*的参数类型声明为 `Request`，**FastAPI** 就能把 `Request` 传递到参数里。

/// tip | "提示"

注意，本例除了声明请求参数之外，还声明了路径参数。

因此，能够提取、验证路径参数、并转换为指定类型，还可以用 OpenAPI 注释。

同样，您也可以正常声明其它参数，而且还可以提取 `Request`。

///

## `Request` 文档

You **don't call it** directly (don't add the parenthesis at the end), you just pass it as a parameter to `Depends()`.

And that function takes parameters in the same way that *path operation functions* do.

/// tip

You'll see what other "things", apart from functions, can be used as dependencies in the next chapter.

///

Whenever a new request arrives, **FastAPI** will take care of:

 & Pydantic `Field` 📨 👐 `FieldInfo` 👍.

`Body` 📨 🎚 🏿 `FieldInfo` 🔗. & 📤 🎏 👆 🔜 👀 ⏪ 👈 🏿 `Body` 🎓.

💭 👈 🕐❔ 👆 🗄 `Query`, `Path`, & 🎏 ⚪️➡️ `fastapi`, 👈 🤙 🔢 👈 📨 🎁 🎓.

///

/// tip

👀 ❔ 🔠 🏷 🔢 ⏮️ 🆎, 🔢 💲 & `Field` ✔️ 🎏 📊 *➡ 🛠️ 🔢* 🔢, ⏮️ `Field` ↩️ `Path`, `Query` & `Body`.

///

## 🚮 ➕ ℹ

👆 💪 📣 ➕ ℹ `Field`, `Query`, `Body`, ♒️. & ⚫️ 🔜 🔌 🏗 🎻 🔗.

Remember that when you import `Query`, `Path`, and others from `fastapi`, those are actually functions that return special classes.

///

/// tip

Notice how each model's attribute with a type, default value and `Field` has the same structure as a *path operation function's* parameter, with `Field` instead of `Path`, `Query` and `Body`.

///

## Add extra information

Before FastAPI 0.108.0, Starlette 0.29.0, the `name` was the first parameter.

Also, before that, in previous versions, the `request` object was passed as part of the key-value pairs in the context for Jinja2.

///

/// tip

By declaring `response_class=HTMLResponse` the docs UI will be able to know that the response will be HTML.

///

/// note | "Technical Details"

```Python hl_lines="4  11  15-16"
{!../../docs_src/templates/tutorial001.py!}
```

/// note | "笔记"

在FastAPI 0.108.0，Starlette 0.29.0之前，`name`是第一个参数。
并且，在此之前，`request`对象是作为context的一部分以键值对的形式传递的。

///

/// tip | "提示"

通过声明 `response_class=HTMLResponse`，API 文档就能识别响应的对象是 HTML。

///

/// note | "技术细节"

您还可以使用 `from starlette.templating import Jinja2Templates`。

### Restart After Crash

But in those cases with really bad errors that crash the running **process**, you would want an external component that is in charge of **restarting** the process, at least a couple of times...

/// tip

...Although if the whole application is just **crashing immediately** it probably doesn't make sense to keep restarting it forever. But in those cases, you will probably notice it during development, or at least right after deployment.

In dit geval is `str` de typeparameter die wordt doorgegeven aan `List` (of `list` in Python 3.9 en hoger).

///

Dat betekent: “de variabele `items` is een `list`, en elk van de items in deze list is een `str`”.

/// tip

Als je Python 3.9 of hoger gebruikt, hoef je `List` niet te importeren uit `typing`, je kunt in plaats daarvan hetzelfde reguliere `list` type gebruiken.

///

```

/// info | "情報"

<a href="https://docs.python.org/3/library/enum.html" class="external-link" target="_blank">Enumerations (もしくは、enums)はPython 3.4以降で利用できます</a>。

///

/// tip | "豆知識"

"AlexNet"、"ResNet"そして"LeNet"は機械学習<abbr title="Technically, Deep Learning model architectures">モデル</abbr>の名前です。

///

### *パスパラメータ*の宣言

次に、作成したenumクラスである`ModelName`を使用した型アノテーションをもつ*パスパラメータ*を作成します:

* `500` and above are for server errors. You almost never use them directly. When something goes wrong at some part in your application code, or server, it will automatically return one of these status codes.

/// tip