query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

## Dieselbe Abhängigkeit mehrmals verwenden

Wenn eine Ihrer Abhängigkeiten mehrmals für dieselbe *Pfadoperation* deklariert wird, beispielsweise wenn mehrere Abhängigkeiten eine gemeinsame Unterabhängigkeit haben, wird **FastAPI** diese Unterabhängigkeit nur einmal pro Request aufrufen.

```

请求 `/unicorns/yolo` 时，路径操作会触发 `UnicornException`。

但该异常将会被 `unicorn_exception_handler` 处理。

接收到的错误信息清晰明了，HTTP 状态码为 `418`，JSON 内容如下：

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}

```

!!! note "技术细节"

    `from starlette.requests import Request` 和 `from starlette.responses import JSONResponse` 也可以用于导入 `Request` 和 `JSONResponse`。

In dem oder den DNS-Server(n) würden Sie einen Eintrag (einen „`A record`“) konfigurieren, um mit **Ihrer Domain** auf die öffentliche **IP-Adresse Ihres Servers** zu verweisen.

Sie würden dies wahrscheinlich nur einmal tun, beim ersten Mal, wenn Sie alles einrichten.

!!! tip "Tipp"

📥, 🚥 👆 📨 `/unicorns/yolo`, *➡ 🛠️* 🔜 `raise` `UnicornException`.

✋️ ⚫️ 🔜 🍵 `unicorn_exception_handler`.

, 👆 🔜 📨 🧹 ❌, ⏮️ 🇺🇸🔍 👔 📟 `418` & 🎻 🎚:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

!!! note "📡 ℹ"
    👆 💪 ⚙️ `from starlette.requests import Request` & `from starlette.responses import JSONResponse`.

しかし、これは`unicorn_exception_handler`で処理されます。

そのため、HTTPステータスコードが`418`で、JSONの内容が以下のような明確なエラーを受け取ることになります:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

!!! note "技術詳細"
    また、`from starlette.requests import Request`と`from starlette.responses import JSONResponse`を使用することもできます。

<div class="termy">

```console
// Use the command "serve" after running "build-all"
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

</div>

## 💯

Hiding your documentation user interfaces in production *shouldn't* be the way to protect your API.

That doesn't add any extra security to your API, the *path operations* will still be available where they are.

If there's a security flaw in your code, it will still exist.

When building web APIs with FastAPI, if there's an error in our code, FastAPI will normally contain it to the single request that triggered the error. 🛡

The client will get a **500 Internal Server Error** for that request, but the application will continue working for the next requests instead of just crashing completely.

### Bigger Errors - Crashes

In Python 3.10 there's also a **new syntax** where you can put the possible types separated by a <abbr title='also called "bitwise or operator", but that meaning is not relevant here'>vertical bar (`|`)</abbr>.

=== "Python 3.10+"

    ```Python hl_lines="1"
    {!> ../../../docs_src/python_types/tutorial008b_py310.py!}

* It contains an `app/main.py` file. As it is inside a Python package (a directory with a file `__init__.py`), it is a "module" of that package: `app.main`.
* There's also an `app/dependencies.py` file, just like `app/main.py`, it is a "module": `app.dependencies`.
* There's a subdirectory `app/routers/` with another file `__init__.py`, so it's a "Python subpackage": `app.routers`.