これは200のHTTPステータスコード（200から299）に似ています。これらの「200」ステータスコードは、何らかの形でリクエスト「成功」であったことを意味します。

400の範囲にあるステータスコードは、クライアントからのエラーがあったことを意味します。

**"404 Not Found"** のエラー（およびジョーク）を覚えていますか？

## `HTTPException`の使用 { #use-httpexception }

HTTPレスポンスをエラーでクライアントに返すには、`HTTPException`を使用します。

### `HTTPException`のインポート { #import-httpexception }

{* ../../docs_src/handling_errors/tutorial001_py310.py hl[1] *}

             Searching for package file structure from directories with
             <font color="#3465A4">__init__.py</font> files
             Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

   <span style="background-color:#007166"><font color="#D3D7CF"> module </font></span>  🐍 main.py

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2018 Square, Inc.
 *
 * Licensed 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

                    req.setFileInformation(new FileBasicInfo(ctime, atime, mtime, 0L, attrs));
                    dh.send(req);
                } else if (dh.hasCapability(SmbConstants.CAP_NT_SMBS)) {
                    // use the open file descriptor
                    dh.send(new Trans2SetFileInformation(dh.getConfig(), dfd.getFid(), attrs, ctime, mtime, atime),
                            new Trans2SetFileInformationResponse(dh.getConfig()));

모든 것이 임의의 깊이로 중첩됩니다.

### 서브모델 정의 { #define-a-submodel }

예를 들어, `Image` 모델을 정의할 수 있습니다:

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[7:9] *}

### 서브모델을 타입으로 사용 { #use-the-submodel-as-a-type }

그리고 이를 어트리뷰트의 타입으로 사용할 수 있습니다:

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

이는 **FastAPI**가 다음과 유사한 본문을 기대한다는 것을 의미합니다:

```JSON
{
    "name": "Foo",

두 경우 모두 다음을 갖게 됩니다:

* `str`인 선택적 쿼리 매개변수 `q`.
* 기본값이 `0`인 `int` 쿼리 매개변수 `skip`.
* 기본값이 `100`인 `int` 쿼리 매개변수 `limit`.

두 경우 모두 데이터는 변환되고, 검증되며, OpenAPI 스키마에 문서화되는 등 여러 처리가 적용됩니다.

## 사용하기 { #use-it }

이제 이 클래스를 사용해 의존성을 선언할 수 있습니다.

{* ../../docs_src/dependencies/tutorial002_an_py310.py hl[19] *}

**FastAPI**는 `CommonQueryParams` 클래스를 호출합니다. 그러면 해당 클래스의 "인스턴스"가 생성되고, 그 인스턴스가 함수의 매개변수 `commons`로 전달됩니다.