83 lines
2.9 KiB
TypeScript
83 lines
2.9 KiB
TypeScript
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import { createAsyncThunk, createSlice, PayloadAction } from '@reduxjs/toolkit'
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import type { AppState, AppThunk } from '../../app/store'
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import { fetchCount } from './counterAPI'
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export interface CounterState {
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value: number
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status: 'idle' | 'loading' | 'failed'
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}
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const initialState: CounterState = {
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value: 0,
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status: 'idle',
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}
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// The function below is called a thunk and allows us to perform async logic. It
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// can be dispatched like a regular action: `dispatch(incrementAsync(10))`. This
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// will call the thunk with the `dispatch` function as the first argument. Async
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// code can then be executed and other actions can be dispatched. Thunks are
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// typically used to make async requests.
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export const incrementAsync = createAsyncThunk(
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'counter/fetchCount',
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async (amount: number) => {
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const response = await fetchCount(amount)
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// The value we return becomes the `fulfilled` action payload
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return response.data
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}
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)
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export const counterSlice = createSlice({
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name: 'counter',
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initialState,
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// The `reducers` field lets us define reducers and generate associated actions
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reducers: {
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increment: (state) => {
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// Redux Toolkit allows us to write "mutating" logic in reducers. It
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// doesn't actually mutate the state because it uses the Immer library,
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// which detects changes to a "draft state" and produces a brand new
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// immutable state based off those changes
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state.value += 1
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},
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decrement: (state) => {
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state.value -= 1
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},
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// Use the PayloadAction type to declare the contents of `action.payload`
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incrementByAmount: (state, action: PayloadAction<number>) => {
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state.value += action.payload
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},
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},
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// The `extraReducers` field lets the slice handle actions defined elsewhere,
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// including actions generated by createAsyncThunk or in other slices.
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extraReducers: (builder) => {
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builder
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.addCase(incrementAsync.pending, (state) => {
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state.status = 'loading'
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})
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.addCase(incrementAsync.fulfilled, (state, action) => {
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state.status = 'idle'
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state.value += action.payload
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})
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},
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})
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export const { increment, decrement, incrementByAmount } = counterSlice.actions
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// The function below is called a selector and allows us to select a value from
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// the state. Selectors can also be defined inline where they're used instead of
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// in the slice file. For example: `useSelector((state: RootState) => state.counter.value)`
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export const selectCount = (state: AppState) => state.counter.value
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// We can also write thunks by hand, which may contain both sync and async logic.
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// Here's an example of conditionally dispatching actions based on current state.
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export const incrementIfOdd =
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(amount: number): AppThunk =>
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(dispatch, getState) => {
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const currentValue = selectCount(getState())
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if (currentValue % 2 === 1) {
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dispatch(incrementByAmount(amount))
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}
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}
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export default counterSlice.reducer
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