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React Native Academy · レッスン

AxiosによるPOST、PUT、DELETE

AxiosのPOSTとPUTでAPIにデータを送り、レスポンスを処理してローカルstateを更新し、サーバーとリストの両方から項目を削除するdeleteアクションを実装します

「AxiosによるPOST、PUT、DELETE」はCoddyKit上の無料React Native Academyレッスンです。 これはレッスン4/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはReact Native Academy学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 React Native Academyコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

CRUD Operations with Axios

Beyond fetching data, most apps need to create, update, and delete resources on a server. Axios provides axios.post, axios.put, axios.patch, and axios.delete methods that map directly to HTTP verbs. Each method returns a Promise resolving to the server's response.

POST: Creating a New Resource

axios.post(url, data) sends a request body as JSON to create a new resource. The second argument is the request body object — Axios automatically serializes it to JSON and sets the Content-Type: application/json header. The server typically responds with the created resource including its assigned ID.

const createPost = async (title, body) => {
  const response = await axios.post(
    'https://jsonplaceholder.typicode.com/posts',
    { title, body, userId: 1 }
  );
  console.log('Created:', response.data);
  // { id: 101, title: '...', body: '...', userId: 1 }
  return response.data;
};

Adding a New Item to State After POST

After a successful POST, add the returned item to your local state array to reflect the creation without a full re-fetch. Use the functional form of setState to safely merge the new item with the existing array. The server-assigned ID is used as the unique key in subsequent renders.

const handleCreate = async (formData) => {
  try {
    const response = await axios.post('/posts', formData);
    const newPost = response.data;
    setPosts((prev) => [newPost, ...prev]);
  } catch (err) {
    setError('Failed to create post');
  }
};

PUT: Replacing a Full Resource

axios.put(url, data) replaces an entire resource with the provided data. Include the resource's ID in the URL and send all fields in the body. PUT is idempotent — calling it multiple times with the same data produces the same result. Use PUT when you are replacing the complete resource, not just updating a few fields.

const updatePost = async (postId, updatedData) => {
  const response = await axios.put(
    '/posts/' + postId,
    updatedData
  );
  return response.data;
};

PATCH: Partial Update

axios.patch(url, data) sends only the changed fields instead of the entire resource. This is more efficient than PUT when you are updating a single field (like a user's avatar or a post's title). Many REST APIs support both PUT and PATCH — check the API documentation to see which one is expected.

// Only update the title, leave other fields untouched
const patchPostTitle = async (postId, newTitle) => {
  const response = await axios.patch(
    '/posts/' + postId,
    { title: newTitle }
  );
  return response.data;
};

Updating State After PUT/PATCH

After a successful update, replace the old item in the state array with the server's returned version. Use Array.map to iterate over the state and swap the matching item. This keeps the local state in sync with the server without a full re-fetch.

const handleUpdate = async (postId, updatedData) => {
  try {
    const response = await axios.put('/posts/' + postId, updatedData);
    const updatedPost = response.data;
    setPosts((prev) =>
      prev.map((p) => (p.id === postId ? updatedPost : p))
    );
  } catch (err) {
    setError('Failed to update post');
  }
};

DELETE: Removing a Resource

axios.delete(url) removes the resource at the given URL. Most APIs return a 200 or 204 (No Content) response on successful deletion. Unlike POST and PUT, DELETE does not send a request body. The third argument to axios.delete can pass config options like auth headers.

const deletePost = async (postId) => {
  await axios.delete('/posts/' + postId);
  console.log('Post deleted');
};

Removing the Item from State After DELETE

After a successful DELETE, filter the item out of your local state array with Array.filter. The UI updates immediately without a round-trip to re-fetch the full list. If the DELETE fails, the error is caught and the item remains in state — showing the user an error message.

const handleDelete = async (postId) => {
  try {
    await axios.delete('/posts/' + postId);
    setPosts((prev) => prev.filter((p) => p.id !== postId));
  } catch (err) {
    setError('Failed to delete post');
  }
};

Optimistic Updates

Optimistic updates update the local state immediately (before the server confirms) to make the UI feel instant. If the request fails, revert to the original state and show an error. This pattern is used by Twtter's like button and Gmail's delete — the action feels instant even over a slow connection.

const handleDelete = async (postId) => {
  const originalPosts = posts;
  // Update immediately
  setPosts((prev) => prev.filter((p) => p.id !== postId));
  try {
    await axios.delete('/posts/' + postId);
  } catch (err) {
    // Revert on failure
    setPosts(originalPosts);
    setError('Delete failed. Please try again.');
  }
};

Uploading Files with FormData

To upload an image or file via POST, create a FormData object, append the file using the React Native URI format, and pass it to axios.post. Set the Content-Type header to multipart/form-data so the server parses it correctly as a file upload rather than JSON.

const uploadAvatar = async (imageUri) => {
  const formData = new FormData();
  formData.append('avatar', {
    uri: imageUri,
    name: 'avatar.jpg',
    type: 'image/jpeg',
  });

  const response = await axios.post('/user/avatar', formData, {
    headers: { 'Content-Type': 'multipart/form-data' },
  });
  return response.data.avatarUrl;
};

Chaining Mutations: Create Then Navigate

After a successful POST or PUT, you often want to navigate the user to the newly created resource's detail screen. Chain the navigation call after the state update in the success path of your try/catch. Pass the new resource's ID or the full object as navigation params.

const handleCreatePost = async (formData) => {
  try {
    const response = await axios.post('/posts', formData);
    const newPost = response.data;
    setPosts((prev) => [newPost, ...prev]);
    navigation.navigate('PostDetail', { postId: newPost.id });
  } catch (err) {
    setError('Failed to create post');
  }
};

Quick Check

Test your understanding of POST, PUT, and DELETE requests with Axios from this lesson.

Lesson Recap

In this lesson you learned: axios.post sends a JSON body to create a resource and returns the created item from the server, axios.put/patch replaces or partially updates a resource — update state with Array.map after success, and axios.delete removes a resource — update state with Array.filter and use optimistic updates for a snappy UX. Next up we explore Redux Toolkit for managing complex application state.

よくある質問

「AxiosによるPOST、PUT、DELETE」レッスンは無料ですか？

はい。「AxiosによるPOST、PUT、DELETE」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、React Native Academyコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 React Native Academyコースには全4レッスンが含まれています。

「AxiosによるPOST、PUT、DELETE」で何を学びますか？

AxiosのPOSTとPUTでAPIにデータを送り、レスポンスを処理してローカルstateを更新し、サーバーとリストの両方から項目を削除するdeleteアクションを実装します ブラウザで直接実行するハンズオンコードでReact Native Academyを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

React Native Academyを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのReact Native Academyは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン4/4です。

「AxiosによるPOST、PUT、DELETE」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このReact Native Academyレッスンでコードを書いて実行できますか？

はい。すべてのReact Native Academyレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

このコースのすべてのレッスン

  1. useEffectフックと依存配列
  2. AxiosによるGETリクエスト
  3. ローディング状態とエラー状態の処理
  4. AxiosによるPOST、PUT、DELETE
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