#
# 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,

 *
 * 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) 2025 Block, 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,

{* ../../docs_src/middleware/tutorial001_py310.py hl[8:9,11,14] *}

/// tip | 豆知識

カスタムの独自ヘッダーは [`X-` プレフィックスを使用](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers)して追加できる点に注意してください。

ただし、ブラウザのクライアントに表示させたいカスタムヘッダーがある場合は、[CORS (Cross-Origin Resource Sharing)](cors.md) の設定に、[StarletteのCORSドキュメント](https://www.starlette.dev/middleware/#corsmiddleware)に記載されているパラメータ `expose_headers` を使用して、それらを追加する必要があります。

///

/// note | 技術詳細

/*
 * Copyright (C) 2025 Block, 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 (C) 2025 Block, 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,

 * </ul>
 *
 * <p>Consumers of this annotation include:
 *
 * <ul>
 *   <li>NullAway, which <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treats it
 *       identically to {@code Nullable}</a> as of version 0.9.9.
 *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>, maybe: It might no longer be

 * </ul>
 *
 * <p>Consumers of this annotation include:
 *
 * <ul>
 *   <li>NullAway, which <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treats it
 *       identically to {@code Nullable}</a> as of version 0.9.9.
 *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>, maybe: It might no longer be

 * </ul>
 *
 * <p>Consumers of this annotation include:
 *
 * <ul>
 *   <li>NullAway, which <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treats it
 *       identically to {@code Nullable}</a> as of version 0.9.9.
 *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>, maybe: It might no longer be

 * </ul>
 *
 * <p>Consumers of this annotation include:
 *
 * <ul>
 *   <li>NullAway, which <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treats it
 *       identically to {@code Nullable}</a> as of version 0.9.9.
 *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>, maybe: It might no longer be