REDUX。我無法理解如何連接定義為擴展 React.Component 的 class 的組件以讀取商店

Question

首先，我讀過這個問題React-redux connect() cannot wrap component defined as a class extending React.Component但我仍然無法理解它，因為連接是在某種上層完成的，但我不明白那個階段。

這是我目前的結構：

reduxStore.js

import { createStore } from "redux";
import rootReducer from "../reducers/index";

const store = createStore(rootReducer);

export default store;

動作類型.js

export const RENDER_LAYOUT_ELEMENT = "REDER_LAYOUT_ELEMENT"

reduxActions.js

import {RENDER_LAYOUT_ELEMENT} from "../constants/action-types"

export function renderLayoutElement(payload){
    return {type: RENDER_LAYOUT_ELEMENT}
};

reduxReducers.js

import {RENDER_LAYOUT_ELEMENT} from "../constants/action-types"

const initialState = {
    renderedEl: {
        heimdall: false,
        skadi: false,
        mercator: false
    }
}

function renderedElReducer(state = initialState, action){
    if(action.type === RENDER_LAYOUT_ELEMENT){
        return Object.assign({},state,{
            renderedEl: state.renderedEl.concat(action.payload)
        })
    }
    return state
}

export default renderedElReducer;

現在我想要的是，讀取我擁有的組件中的 renderedEl initialState 。 根據我的理解，我需要將該組件連接到商店，然后使用 mapStateToProps 它將讀取全局 state（商店）

所以我 go 到我的組件並嘗試連接它，但我不知道在哪里做。

該組件很大，但基本上我試圖停止使用 renderedEl 的 state，以從商店讀取它。 state im cur.netly using 位於構造函數中，它應該消失，因為它現在將從商店中讀取。

在渲染中，樣式的條件部分現在不會根據狀態設置，而是根據商店設置。 我本來打算做所有這些，但問題是，現在我卡在了如何將這個組件連接到商店上。 我看到的所有教程都與某種功能組件相關，而不是 class 組件

  import React, { Component, useState } from "react";
import brand from "../images/valhallaNaranja.png";
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'

import { faArrowAltCircleLeft, faArrowAltCircleRight, faUser } from '@fortawesome/free-regular-svg-icons'
import { faColumns } from '@fortawesome/free-solid-svg-icons'
import './css/Sidebar.css'
import { isAdmin } from "../services/userCheck.js"

//select
const mapStateToProps = state => {
    return { renderedEl: state.renderedEl }
}

export default class SideBar extends Component {
    constructor(props) {
        super(props);
        this.state = {
            retracted: this.props.retracted,
            isAdmin: false,
            isHovering: false,
            //THIS STATE IS WHAT IM TRYING TO REPLACE BY READING FROM THE STORE
            renderedEl: {
                heimdall: false,
                skadi: false,
                mercator: false
            }
        }

        this.hoverTrue = this.hoverTrue.bind(this);
        this.hoverFalse = this.hoverFalse.bind(this);
    }



    componentDidMount() {
        if (isAdmin()) {
            this.setState({
                isAdmin: true
            })
        }
    }

    componentDidUpdate() {
        if (this.state.retracted != this.props.retracted) {
            this.setState({
                retracted: this.props.retracted
            })
        }
    }

    renderEl = (el) => {
        var elementName = el.target.getAttribute('id');
        var renderedElements = this.state.renderedEl;

        for (let key in renderedElements) {
            if (key == elementName) {
                renderedElements[key] = true
            }
        }
        this.setState({
            renderEl: renderedElements
        })
    }

    hoverTrue() {
        this.setState({
            isHovering: true
        })
    }

    hoverFalse() {
        this.setState({
            isHovering: false
        })
    }

    render() {

        let navbar_brand = this.state.retracted ? "navbar-brand-retracted" : "navbar-brand";
        let img_redie = this.state.retracted ? "img-redie-retracted" : "img-redie";
        let home_icon = this.state.retracted ? "divicon homeicon-retracted" : "divicon homeicon";
        let register_icon = this.state.retracted ? "divicon divicon2 registericon-retracted" : "divicon divicon2 registericon";
        let expand_icon = this.state.retracted ? "divicon-no-hover divicon2 expandicon-retracted" : "divicon divicon2 expandicon";

    //THOSE STATES WILL BE READ NOW FROM THE STORE
        let skadiRendered = this.state.renderedEl.skadi ? "bubbletext bubbletext-rendered" : "bubbletext";
        let heimdallRendered = this.state.renderedEl.heimdall ? "bubbletext bubbletext-rendered" : "bubbletext";
        let mercatorRendered = this.state.renderedEl.mercator ? "bubbletext bubbletext-rendered" : "bubbletext";

        let layoutAppVisualSelector = this.props.history.location.pathname == "/layout" ? "divicon divicon2 expandicon divicon-layout" : "divicon divicon2 expandicon";
        return (
            <div id="sidebar" className={this.state.retracted ? 'sidebar-retracted' : 'sidebar-expanded'}>
                <div /*routerLink=""*/ className={navbar_brand}>
                    <img alt="Reddie" src={brand} width="60" height="60" className={img_redie} />
                </div>

                <ul className="nav nav3 navbar-nav">
                    <li>
                        {/* Home icon */}
                        <div className={home_icon} onClick={() => this.props.history.push('/')}>
                            <svg className="svgicon-sidebar" viewBox="0 0 14 14" >
                                <path d="M13.9 5.7L7.2.8c-.1-.1-.3-.1-.4 0L.1 5.7c-.1.1-.1.3 0 .5s.3.2.5.1L7 1.6l6.4 4.7c.1 0 .1.1.2.1s.2-.1.3-.1c.1-.3.1-.5 0-.6" />
                                <path d="M12.1 6.4c-.2 0-.4.2-.4.4v5.8H8.8V9.4c0-1-.8-1.8-1.8-1.8s-1.8.8-1.8 1.8v3.2H2.3V6.7c0-.2-.2-.4-.4-.4s-.4.2-.4.4v6.2c0 .2.2.4.4.4h3.6c.2 0 .3-.1.4-.3V9.4c0-.6.5-1.1 1.1-1.1.6 0 1.1.5 1.1 1.1v3.5c0 .2.2.3.4.3h3.6c.2 0 .4-.2.4-.4V6.7c0-.2-.2-.3-.4-.3" />
                            </svg>
                        </div>
                    </li>

                    {this.state.isAdmin ? <li>
                        <div className={register_icon} onClick={() => this.props.history.push('/admin')}>
                            <FontAwesomeIcon className="registerIcon" icon={faUser} />
                        </div>
                    </li> : null}


                    {(this.props.history.location.pathname != "/layout") && (this.props.history.location.pathname != "/skadi") && (this.props.history.location.pathname != "/heimdall") && (this.props.history.location.pathname != "/mercator") ? null : <li>
                        <div className={layoutAppVisualSelector} onMouseEnter={this.hoverTrue}
                            onMouseLeave={this.hoverFalse} >
                            <FontAwesomeIcon className="registerIcon" icon={faColumns} onClick={() => this.props.history.push({ pathname: '/layout', state: { comeFrom: this.props.history.location.pathname } })} />
                            {(this.state.isHovering && this.props.history.location.pathname == "/layout") ? <div className="speech-bubble" onMouseLeave={this.hoverFalse}
                                onMouseEnter={this.hoverTrue}>
                                <span id="heimdall" className={heimdallRendered} onClick={(el) => this.renderEl(el)}>Heimdall</span> <br /> <span className={skadiRendered} id="skadi" onClick={(el) => this.renderEl(el)}>Skadi</span> <br /> <span id="mercator" className={mercatorRendered} onClick={(el) => this.renderEl(el)}>Mercator</span>
                            </div> : null}

                        </div>

                    </li>}

                    {(this.state.retracted) || ((this.props.history.location.pathname == "/") || (this.props.history.location.pathname == "/register")) || (this.props.history.location.pathname == "/admin") || (this.props.history.location.pathname == "/layout") ? null : <li>
                        <div className="divicon divicon2 expandicon " onClick={this.props.retract}>
                            <FontAwesomeIcon className="registerIcon" icon={faArrowAltCircleLeft} />
                        </div>
                    </li>}



                </ul>

                {this.state.retracted ? <div className="expandicon-retracted-container"> <FontAwesomeIcon className="expandicon-retracted" icon={faArrowAltCircleRight} onClick={this.props.unretract} /> </div> : null}

            </div>

        )
    }
}

我 go 如何連接該組件？

Answer 1

首先你需要用 redux Provider包裝一個根組件（最推薦的 index.js 或 App.js ...）

---

  import { Provider } from 'react-redux'

 <Provider store={store}>
    <App />
</Provider>

---

如此之后，為所有在此之下的部分提供了存儲，並且可以像那樣connect

---

   import { connect } from 'react-redux'

   const mapStateToProps = state => {
    return { renderedEl: state.renderedEl }
   }

  class SideBar extends Component {
      componentDidMount() {
         console.log(this.props.renderedEL)
     }
   }

 export default connect(mapStateToProps)(SideBar)

---

至於你的動作，將動作dispatch給減速器

---

export function renderLayoutElement(payload){
   return dispatch => dispatch({type: RENDER_LAYOUT_ELEMENT})
 }

---

Answer 2

僅出於測試目的export class SideBar [...] ，但export default connect(mapStateToProps)(SideBar) ，它將您的組件連接到redux state 並將減少的 state 分配給道具。

編輯：您要查找的文檔位於此處。