redux 实现弹出框案例

实现效果,点击显示按钮出现弹出框,点击关闭按钮隐藏弹出框

  1. 新建弹出框组件 src/components/Modal.js, 在index.js中引入app组件,在app中去显示计数器和弹出框组件
function Modal ({ showState, show, hide }) {
    const styles = {
        width: 200,
        height: 200,
        position: 'absolute',
        top: '50%',
        left: '50%',
        marginTop: -100,
        marginLeft: -100,
        backgroundColor: 'skyblue',
    }
    return <div>
        <button>显示</button>
        <button>隐藏</button>
        <div  style={styles}></div>
    </div>
}
  1. 弹出框组件显示隐藏是一个状态,所以我们存储到store中,命名为show,因为需要出发action来修改store中的状态所系我们需要创建modal.actions.js文件,来存储控制显示隐藏的action,我们还是把显示与隐藏aciton的type定义为常量方便导入使用
// src/store/const/modal.const.js
export const SHOWMODAL = 'showModal'
export const HIDEMODAL = 'hideModal'

// src/store/actions/modal.actions.js
import { SHOWMODAL, HIDEMODAL} from './../const/modal.const'

export const show = () => ({type: SHOWMODAL})
export const hide = () => ({type: HIDEMODAL})

// src/store/reducers/counter.reducers.js
import { INCREMENT, DECREMENT } from './../const/counter.const'
import { SHOWMODAL, HIDEMODAL } from './../const/modal.const'

const initialState = {
    count: 0,
    // 增加控制modal 显示隐藏显示的状态,默认为隐藏状态
    show: false
}
// eslint-disable-next-line import/no-anonymous-default-export
export default (state = initialState, action) => {
    switch (action.type) {
        case INCREMENT:
            return {
                count: state.count + action.payload
            }
        case DECREMENT:
            return {
                count: state.count - action.payload
            }
        case SHOWMODAL:
            return {
                show: true
            }
        case HIDEMODAL:
            return {
                show: false
            }

        default:
            return state
    }
}
  1. 弹框的显示隐藏状态用display属性控制所以我们需要把状态映射到props属性中,因为show状态与show显示方法重名了,所以给show状态起一个别名,利用 bindActionCreators 方法把 执行 dispatch 提交actions的方法映射到props中
import React from 'react'
import { connect } from 'react-redux'
import * as modalActions from './../store/actions/modal.actions'
import { bindActionCreators } from 'redux'

function Modal ({ showState, show, hide }) {
    const styles = {
        width: 200,
        height: 200,
        position: 'absolute',
        top: '50%',
        left: '50%',
        marginTop: -100,
        marginLeft: -100,
        backgroundColor: 'skyblue',
        // 增加控制显示隐藏的css样式
        display: showState ? 'block' : 'none'
    }
    return <div>
        <button onClick={show}>显示</button>
        <button onClick={hide}>隐藏</button>
        <div  style={styles}></div>
    </div>
}
// 映射显示英藏状态到props中
const mapStateToProps = state => {
    return {
        showState: state.show
    }
}
// 把提交actions方法映射到组件props中
const mapDispacthToProps = dispatch => bindActionCreators(modalActions, dispatch)
export default connect(mapStateToProps,mapDispacthToProps)(Modal)

通过上面我们发现在点击显示与隐藏之后计数器组件中的数字不见了,因为我们在执行显示与隐藏的方法中并没有返回 计数器的状态所以这个状态丢失掉了,我们需要在更改状态的时候去补上原有的状态

  1. 补上原有状态
export default (state = initialState, action) => {
    switch (action.type) {
        case INCREMENT:
            return {
                ...state,
                count: state.count + action.payload
            }
        case DECREMENT:
            return {
                ...state,
                count: state.count - action.payload
            }
        case SHOWMODAL:
            return {
                ...state,
                show: true
            }
        case HIDEMODAL:
            return {
                ...state,
                show: false
            }

        default:
            return state
    }
}

这个时候我们的计数器与弹出框组件都已经正常了,但是我们发现reducer函数随着actions动作越来越多变的越来越臃肿,在状态越来越多以后将会变得无法维护

拆分reducer 函数

在计数器与弹出框案例中,在reducer函数中,我们既匹配到了计数器案例中的actions,又匹配到了弹出框案例中的actions 这样reducer中的代码将会越来越庞大,越来越臃肿,所以我们接下来拆分reducer,拆分reducer我们需要用到 combineReducers 方法,这个方法要求我们传递一个对象 这个对象是状态对象,返回值是合并后的reducer

  1. 创建 src/store/reducers/modal.reducers.js 文件,把弹出框的reducer抽离出来
import { SHOWMODAL, HIDEMODAL } from './../const/modal.const'

const initialState = {
    show: false
}

// eslint-disable-next-line import/no-anonymous-default-export
export default (state = initialState, action) => {
    switch (action.type) {
        
        case SHOWMODAL:
            return {
                ...state,
                show: true
            }
        case HIDEMODAL:
            return {
                ...state,
                show: false
            }

        default:
            return state
    }
}
  1. 创建src/store/reducers/root.reducers.js 文件,用于合并计数器与弹出框的reducer
import { combineReducers } from 'redux'
import CounterReducers from './counter.reducers'
import ModalReducers from './modal.reducers'

// 要求我们传递一个对象 这个对象是状态对象
// 这样写了之后 状态的结构将是这样 counter: { count: 0 } modaler: { show: false }
export default combineReducers({
    counter: CounterReducers,
    modaler: ModalReducers
})
  1. 因为使用 combineReducers 合并reducer的时候改变了state的结构所以我们需要在组件中去更改获取state的方式
// src/components/Count.js
const mapStateProps = ({ counter }) => ({
    count: counter.count,
    a: '1'
})
// src/components/Modal.js
const mapStateToProps = ({ modaler }) => {
    return {
        showState: modaler.show
    }
}