Thunk Asinkron dengan createAsyncThunk
Ambil data dari API di dalam createAsyncThunk, tangani siklus hidup tertunda/berhasil/ditolak dalam extraReducers milik irisan, lalu tampilkan status asinkron di UI.
Thunk Asinkron dengan createAsyncThunk adalah pelajaran React Native Academy gratis di CoddyKit. Ini adalah pelajaran 4 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar React Native Academy, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus React Native Academy mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Why Do We Need Async Thunks?
Redux reducers must be pure synchronous functions — they cannot make API calls or run async code. To fetch data from a server and store the result in Redux, we need an async thunk: a function that dispatches plain actions before and after an async operation. Redux Toolkit's createAsyncThunk handles this pattern with minimal boilerplate.
Creating an Async Thunk
createAsyncThunk accepts two arguments: a string action type prefix and a payload creator function that performs the async work and returns the result. It automatically dispatches pending, fulfilled, or rejected actions based on whether the payload creator's promise resolves or rejects.
import { createAsyncThunk } from '@reduxjs/toolkit';
import axios from 'axios';
export const fetchPosts = createAsyncThunk(
'posts/fetchPosts', // action type prefix
async (page: number) => { // payload creator
const response = await axios.get('https://api.example.com/posts?page=' + page);
return response.data; // this becomes action.payload
}
);The Three Lifecycle Actions
For every createAsyncThunk call, RTK automatically creates three action creators: thunk.pending (dispatched when the async call starts), thunk.fulfilled (dispatched with the returned data when it succeeds), and thunk.rejected (dispatched with the error when it fails). You handle each case in extraReducers.
// These are created automatically:
fetchPosts.pending.type // 'posts/fetchPosts/pending'
fetchPosts.fulfilled.type // 'posts/fetchPosts/fulfilled'
fetchPosts.rejected.type // 'posts/fetchPosts/rejected'Handling Lifecycle in extraReducers
Use the builder.addCase pattern inside extraReducers to handle each lifecycle action. In the pending case set a loading flag, in fulfilled store the data and clear loading, and in rejected store the error message and clear loading. This gives every async operation a consistent state machine.
const postsSlice = createSlice({
name: 'posts',
initialState: { items: [], status: 'idle', error: null },
reducers: {},
extraReducers: (builder) => {
builder
.addCase(fetchPosts.pending, (state) => {
state.status = 'loading';
})
.addCase(fetchPosts.fulfilled, (state, action) => {
state.status = 'succeeded';
state.items = action.payload;
})
.addCase(fetchPosts.rejected, (state, action) => {
state.status = 'failed';
state.error = action.error.message ?? 'Unknown error';
});
},
});Dispatching an Async Thunk from a Component
Dispatch an async thunk exactly like a regular action — pass it to dispatch(). The thunk returns a Promise, so you can await it or chain .then() if you need to react after the async operation completes inside the component. Use useEffect to dispatch it on mount.
import { useEffect } from 'react';
import { useAppDispatch, useAppSelector } from '../../store/hooks';
import { fetchPosts } from './postsSlice';
export default function PostsScreen() {
const dispatch = useAppDispatch();
const { items, status, error } = useAppSelector((s) => s.posts);
useEffect(() => {
dispatch(fetchPosts(1));
}, [dispatch]);
if (status === 'loading') return <ActivityIndicator />;
if (status === 'failed') return <Text>{error}</Text>;
return <FlatList data={items} /* ... */ />;
}Passing Arguments to the Thunk
The payload creator function receives the first argument passed to the thunk when dispatched, and a second argument called thunkAPI that provides getState, dispatch, rejectWithValue, and more. Use getState to read current Redux state inside the thunk, for example to include an auth token in a request header.
export const createPost = createAsyncThunk(
'posts/create',
async (postData: { title: string; body: string }, thunkAPI) => {
const state = thunkAPI.getState() as RootState;
const token = state.user.token;
const response = await axios.post('/posts', postData, {
headers: { Authorization: 'Bearer ' + token },
});
return response.data;
}
);Handling Errors with rejectWithValue
By default, the rejected action contains only the serialized error message. If you need to pass a custom error payload — such as an HTTP status code or server-provided error message — use thunkAPI.rejectWithValue() inside a try-catch block. The value you pass becomes action.payload in the rejected case.
export const fetchUser = createAsyncThunk(
'user/fetch',
async (userId: string, { rejectWithValue }) => {
try {
const response = await axios.get('/users/' + userId);
return response.data;
} catch (err: any) {
return rejectWithValue(err.response.data.message);
}
}
);
// In extraReducers:
.addCase(fetchUser.rejected, (state, action) => {
state.error = action.payload as string; // custom error message
})Unwrapping the Dispatch Result
Dispatching a thunk returns a special Promise that you can unwrap() to get the fulfilled value or throw the error. This is useful when you need the result directly in the component — for example, navigating to a new screen after a successful API call without storing transient navigation state in Redux.
async function handleSubmit() {
try {
const result = await dispatch(createPost({ title, body })).unwrap();
navigation.navigate('PostDetail', { id: result.id });
} catch (err) {
Alert.alert('Error', 'Failed to create post');
}
}Cancelling an In-Flight Request
createAsyncThunk supports request cancellation via an AbortController. The thunkAPI.signal is an AbortSignal that you can pass to Axios or Fetch. When the component unmounts or the user navigates away, calling the thunk's abort() method cancels the pending request and dispatches the rejected action with AbortError.
export const fetchData = createAsyncThunk(
'data/fetch',
async (_, { signal }) => {
const response = await axios.get('/data', { signal });
return response.data;
}
);
// In component useEffect:
useEffect(() => {
const promise = dispatch(fetchData());
return () => promise.abort(); // cancel on unmount
}, []);Status-Driven UI Patterns
The status field in your slice state acts as a state machine with four values: idle, loading, succeeded, and failed. Pattern-match on this value in your component to show the right UI for each state. This prevents showing stale data and empty lists simultaneously, giving users clear feedback throughout the async lifecycle.
function renderContent() {
switch (status) {
case 'idle':
return <Text>Press button to load</Text>;
case 'loading':
return <ActivityIndicator size='large' />;
case 'succeeded':
return <FlatList data={items} renderItem={renderItem} />;
case 'failed':
return <Text style={styles.error}>{error}</Text>;
}
}Multiple Thunks for CRUD Operations
Real apps typically need separate thunks for each HTTP verb. Create one thunk per operation — fetchItems, addItem, updateItem, deleteItem — and handle each in extraReducers. After a successful mutation, update the local items array in the fulfilled handler so the UI stays in sync without re-fetching the entire list.
.addCase(deleteItem.fulfilled, (state, action) => {
state.items = state.items.filter((item) => item.id !== action.payload);
})
.addCase(addItem.fulfilled, (state, action) => {
state.items.push(action.payload);
})
.addCase(updateItem.fulfilled, (state, action) => {
const index = state.items.findIndex((i) => i.id === action.payload.id);
if (index !== -1) state.items[index] = action.payload;
})Quick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: createAsyncThunk wraps async operations and dispatches pending/fulfilled/rejected lifecycle actions automatically, extraReducers with builder.addCase handles each lifecycle to update loading and error state, and rejectWithValue lets you pass custom error data to the rejected handler. Next up we explore Zustand, a lightweight alternative to Redux.
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Thunk Asinkron dengan createAsyncThunk” gratis?
Ya — teks lengkap “Thunk Asinkron dengan createAsyncThunk” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus React Native Academy, upgrade ke CoddyKit PRO. Kursus React Native Academy mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Thunk Asinkron dengan createAsyncThunk”?
Ambil data dari API di dalam createAsyncThunk, tangani siklus hidup tertunda/berhasil/ditolak dalam extraReducers milik irisan, lalu tampilkan status asinkron di UI. Kamu berlatih React Native Academy dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai React Native Academy?
Tidak diperlukan pengalaman sebelumnya. React Native Academy di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 4 dari 4.
Berapa lama pelajaran “Thunk Asinkron dengan createAsyncThunk” memakan waktu?
Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran React Native Academy ini?
Ya. Setiap pelajaran React Native Academy menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Menyiapkan Penyimpanan Redux dan Provider
- Membuat Irisan dengan createSlice
- Membaca Keadaan dengan useSelector
- Thunk Asinkron dengan createAsyncThunk