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[英]pass component’s state to mapDispatchToProps React/Redux
[英]redux mapDispatchToProps not updating state
我是 redux 的新手,遇到了 mapDispatchToProps 的問題,我的 react 應用程序中有一個具有不同 div 的組件,每次用戶單擊 div 時,它應該通過參數更改所選顏色,然后再次作為支柱。
我從最初的 state 獲得道具,但無法讓 mapDispatchToProps 正常工作。 似乎有不同的方法來處理 mapDispatchToProps,我嘗試了一些但沒有工作,這就是我目前所擁有的,沒有錯誤但仍然無法正常工作
組件:
import React from 'react';
import { connect } from 'react-redux';
import { changeSelectedColor } from '../actions/actions';
const ColorPalette = ({ selectedColor, changeSelectedColor }) => {
return(
<div>
<div className='flex justify-center mb-2'>
<p>Selected color: {selectedColor}</p>
</div>
<div className='flex justify-center mb-2'>
<button onClick={() => changeSelectedColor('test')} className='border border-black'>
click to change
</button>
</div>
</div>
)
}
const mapStateToProps = (state) => {
return {
selectedColor: state.colorReducer.selectedColor,
}
}
const mapDispatchToProps = (dispatch) => {
return {
changeSelectedColor: (color) => dispatch(changeSelectedColor(color))
}
}
export default connect(mapStateToProps, mapDispatchToProps)(ColorPalette);
減速機:
import { combineReducers } from "redux";
const initialState = {
selectedColor: 'black',
};
const colorReducer = (state = initialState, action) => {
switch(action.payload) {
case 'SET_SELECTED_COLOR':
console.log('changing color to ', action)
return {...state, selectedColor: action.payload};
default:
return state;
}
}
export default combineReducers({
colorReducer,
});
那個行動:
export const changeSelectedColor = (color) => {
return {
type: 'SET_SELECTED_COLOR',
payload: color
}
}
我也嘗試過將 mapDispatchToProps 作為 object 傳遞,在這種情況下,如果我理解正確,每個 function 都應該用調度自動包裝? 並且沒有傳遞第二個參數來連接並將調度作為道具,直接在點擊時調度動作,但就像我說的兩種方法都失敗了
問題來自您的減速器:
const colorReducer = (state = initialState, action) => {
switch(action.type) { // <== here should be type not payload
case 'SET_SELECTED_COLOR':
console.log('changing color to ', action)
return {...state, selectedColor: action.payload};
default:
return state;
}
}
建議(與答案無關)
編寫您的連接函數,如下所示:
const mapStateToProps = ({ colorReducer: { selectedColor } = {} }) => ({
selectedColor,
});
const mapDispatchToProps = dispatch => ({
changeSelectedColor: color => dispatch(changeSelectedColor(color)),
});
還有你的動作和減速器:
export const changeSelectedColor = payload => ({
type: 'SET_SELECTED_COLOR',
payload,
});
const colorReducer = (state = initialState, { type, payload }) => {
switch (type) {
case 'SET_SELECTED_COLOR':
return { ...state, selectedColor: payload };
default:
return state;
}
};
在 ReactJS 中使用重組分配,它很常見,使您的代碼更具可讀性和更好的調試性。
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