状态未更新

Question

我正在为一个简单的计算器编写react-redux代码。这是我的组件文件

import React from 'react';
import {connect} from 'react-redux';

class Calculator extends React.Component{
    render(){
        return(
        <div className="text-center">
            <div>
                <div>
                    <button name='1' value='1' onClick={()=>this.props.addition('1')}>1</button>
                    <button name='2' value='2' onClick={()=>this.props.addition('2')}>2</button>
                    <button name='3' value='3' onClick={()=>this.props.addition('3')}>3</button>
                </div>
                <div>
                    <button name='4' value='4' onClick={()=>this.props.addition('4')}>4</button>
                    <button name='5' value='5' onClick={()=>this.props.addition('5')}>5</button>
                    <button name='6' value='6' onClick={()=>this.props.addition('6')}>6</button>
                </div>
                <div>
                    <button name='7' value='7' onClick={()=>this.props.addition('7')}>7</button>
                    <button name='8' value='8' onClick={()=>this.props.addition('8')}>8</button>
                    <button name='9' value='9' onClick={()=>this.props.addition('9')}>9</button>
                </div>
                <div>
                    <button name='+' value='+' onClick={()=>this.props.addition('+')}>+</button>
                    <button name='0' value='0' onClick={()=>this.props.addition('0')}>0</button>
                    <button name='-' value='-' onClick={()=>this.props.addition('-')}>-</button>
                </div>
                <div>
                    <button name='/' value='/' onClick={()=>this.props.addition('/')}>/</button>
                    <button name='evalu' value='evalu' onClick={()=>this.props.evaluation('=')}>=</button>
                    <button name='*' value='*' onClick={()=>this.props.addition('*')}>*</button>
                </div>
                <div>
                    <button name='cler' value='cler' onClick={()=>this.props.addition('clear')}>clear</button>
                    <button name='bs' value='bs' onClick={()=>this.props.addition('bs')}>del</button>
                </div>
            </div>
        </div>
        )
    }
}

const matchStatestoProps = state =>{
    return {expression:state.expression}
}

const matchDispatchtoProps = dispatch =>{
    return {
        addition: (data)=> dispatch({type:'ADD',payload:data}),
        evaluation: ()=>dispatch({type:'EVAL'})
    }
}

export default connect(matchStatestoProps,matchDispatchtoProps)(Calculator);

这是我的减速机：

    const defaultState={
    expression:''
};

var rootReducer = (state=defaultState, {action,payload}) =>{
    switch (action){
        case 'ADD':
        return {expression:state.expression+payload};
        default: return defaultState;
    }
}

export default rootReducer;

现在，当我单击按钮时，它正在触发操作，但是状态没有得到更新。它仍然是空的。有人可以帮我吗？

这是redux商店的屏幕截图：

Answer 1

您需要从动作对象获取类型

var rootReducer = (state=defaultState,{type, payload}) =>{
    switch (type){
        case 'ADD':
        return {expression:state.expression+payload};
        default: return defaultState;
    }
}

Answer 2

您正在通过键type而不是键action传递操作，因此不要破坏这样的参数：

var rootReducer = (state = defaultState, { action, payload }) =>{

您应该这样做

var rootReducer = (state = defaultState, { type, payload }) =>{

然后切换type而不是action。