```

## Einen `websocket` erstellen

Erstellen Sie in Ihrer **FastAPI**-Anwendung einen `websocket`:

```Python hl_lines="1  46-47"
{!../../docs_src/websockets/tutorial001.py!}
```

/// note | "Technische Details"

Sie können auch `from starlette.websockets import WebSocket` verwenden.

⚫️ 🔜 🔬 🗄 ⏮️ `anyOf`.

👈, ⚙️ 🐩 🐍 🆎 🔑 <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>:

/// note

🕐❔ ⚖ <a href="https://docs.pydantic.dev/latest/concepts/types/#unions" class="external-link" target="_blank">`Union`</a>, 🔌 🏆 🎯 🆎 🥇, ⏩ 🌘 🎯 🆎. 🖼 🔛, 🌖 🎯 `PlaneItem` 👟 ⏭ `CarItem` `Union[PlaneItem, CarItem]`.

///

{!../../docs_src/query_params/tutorial002.py!}
```

이 경우 함수 매개변수 `q`는 선택적이며 기본값으로 `None` 값이 됩니다.

/// check | "확인"

**FastAPI**는 `item_id`가 경로 매개변수이고 `q`는 경로 매개변수가 아닌 쿼리 매개변수라는 것을 알 정도로 충분히 똑똑합니다.

///

/// note | "참고"

FastAPI는 `q`가 `= None`이므로 선택적이라는 것을 인지합니다.

`Union[str, None]`에 있는 `Union`은 FastAPI(FastAPI는 `str` 부분만 사용합니다)가 사용하는게 아니지만, `Union[str, None]`은 편집기에게 코드에서 오류를 찾아낼 수 있게 도와줍니다.

///

## 쿼리 매개변수 형변환

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

### Notable Env Vars

| Env Var            | Default         | Purpose                                                                                                                                       |

allowing a racing thread to read 1 as well.
</p>

<p>
Note that all these optimizations are permitted in C/C++ compilers:
a Go compiler sharing a back end with a C/C++ compiler must take care
to disable optimizations that are invalid for Go.
</p>

<p>
Note that the prohibition on introducing data races
does not apply if the compiler can prove that the races

          'errors.\n' %
          (android_ndk_home_path, ndk_version, _SUPPORTED_ANDROID_NDK_VERSIONS))
  write_action_env_to_bazelrc('ANDROID_NDK_VERSION', ndk_version)

  # Now grab the NDK API level to use. Note that this is different from the
  # SDK API level, as the NDK API level is effectively the *min* target SDK
  # version.
  meta = open(os.path.join(android_ndk_home_path, 'meta/platforms.json'))
  platforms = json.load(meta)

    }
    return (byte) value;
  }

  /**
   * Compares the two specified {@code byte} values. The sign of the value returned is the same as
   * that of {@code ((Byte) a).compareTo(b)}.
   *
   * <p><b>Note:</b> this method behaves identically to {@link Byte#compare}.
   *
   * @param a the first {@code byte} to compare
   * @param b the second {@code byte} to compare

## `Header`のパラメータの宣言

次に、`Path`や`Query`、`Cookie`と同じ構造を用いてヘッダーのパラメータを宣言します。

最初の値がデフォルト値で、追加の検証パラメータや注釈パラメータをすべて渡すことができます。

```Python hl_lines="9"
{!../../docs_src/header_params/tutorial001.py!}
```

/// note | "技術詳細"

`Header`は`Path`や`Query`、`Cookie`の「姉妹」クラスです。また、同じ共通の`Param`クラスを継承しています。

しかし、`fastapi`から`Query`や`Path`、`Header`などをインポートする場合、それらは実際には特殊なクラスを返す関数であることを覚えておいてください。

///

/// info | "情報"