流程如下：

1. 点击 CarouselItem ，触发 onClick={this.handleId 。

2. handleId 接受 id，它是被点击的 CarouselItem 的一个 prop>

3. this.props.dispatch(fetchRecon(movieId)); 将执行 AJAX 操作，该操作将返回数据

4. 并在 Redux 状态中，将最初为 moviesRecon:[] 的属性设置为 moviesRecon:[data] 。 handleId 还会使用 this.props.history.push(`/movie-detail?query=${movieId}`);

将我路由到新页面

5. 我现在应该位于组件 MovieDetailPage 上，该组件当前正在使用 Carousel 组件的模拟数据。理想情况下，我应该为 Carousel 的电影 prop 传递 this.props.movi​​esRecon 。

尝试这样做会给我以下错误：

TypeError: Cannot read property 'map' of undefined
 const carousel = this.props.movies.map((item, index) => {
| ^  51 |         return (
  52 |             <CarouselItem data={item} index={index} key={this.props.movies[index].id} id={this.props.movies[index].id} />
  53 |         );

以下是我认为相关的组件： CarouselItem.js

import React from 'react';
import './CarouselItem.css';
import { connect } from 'react-redux';
import { Link } from 'react-router-dom';
import { fetchRecon } from '../../actions/index';
import { withRouter } from 'react-router-dom';

export class CarouselItem extends React.Component{

    handleId = e => {
        let movieId = this.props.id
        console.log("carousel item", movieId);
        this.props.dispatch(fetchRecon(movieId));
        this.props.history.push(`/movie-detail?query=${movieId}`);


    }

    render() {

        let genres = this.props.genres;
        let genreList = this.props.genres.length;

        function getGenreText(id) {
            for (let i = 0; i < genreList; i++) {
                if (genres[i].id == id) {
                    return genres[i].name;
                }
            }
        }

        if (this.props.data) {
            return (
                <div className="movieContainer" onClick={this.handleId}>
                    <img className="moviePoster" src={`https://image.tmdb.org/t/p/w500/${this.props.data.poster_path}`} alt={this.props.data.title} />
                    <h3 className="movieName">{this.props.data.title}</h3>
                    <p className="movieGenre">{getGenreText(this.props.data.genre_ids[0])}</p>
                </div>

            );
        }   
    }
}

const mapStateToProps = state => ({
    genres: state.app.genres
});

export default connect(mapStateToProps)(withRouter(CarouselItem));

Carousel.js

import React from 'react';
import CarouselItem from '../CarouselItem/CarouselItem';
import './Carousel.css';
import Slider from "react-slick";
import "slick-carousel/slick/slick.css";
import "slick-carousel/slick/slick-theme.css";

export class Carousel extends React.Component {

  componentDidMount() {
    // the trick
    setTimeout(() => {
      this.forceUpdate();
    }, 50);
  }
    render(){


        console.log("carousel probs", this.props);
        const carousel = this.props.movies.map((item, index) => {
            return (
                <CarouselItem data={item} index={index} key={this.props.movies[index].id} id={this.props.movies[index].id} />
            );
        });

        return (
            <div className="inner-carousel">
            <h2>{this.props.title}</h2>
                <Slider {...settings}>
                    {carousel}
                </Slider>
                <hr className="carousel-divider"/>
            </div>
        )
    }
}

MovieDetailPage.js

import React from 'react';
import { connect } from 'react-redux';
import { Carousel } from '../Carousel/Carousel';
import { withRouter } from 'react-router-dom';
import {fetchRecon} from '../../actions/index';
import { recommended } from './mock';
import { movieDetails } from './mockdetails';
import './MovieDetailPage.css';

export class MovieDetailPage extends React.Component {

    componentDidMount() {
        window.scrollTo(0, 0);

        window.onpopstate = () => {
            const params = (new URL(document.location)).searchParams;
            const clickedMovie = params.get("query");
            console.log('here', clickedMovie);
        }
        const params = (new URL(document.location)).searchParams;
        const movieId = params.get("query");
        console.log('here', movieId);

        // this.props.dispatch(fetchRecon(movieId));
    }


    render() {
        console.log('movie detail', this.props.moviesRecon, this.props)
        return (
            <div className="movieDetail">
                <div className="movieDetail-container">
                    <img className="movieDetail-bg" src={`https://image.tmdb.org/t/p/original/or06FN3Dka5tukK1e9sl16pB3iy.jpg`} />
                </div>
                <div className="main-details">
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={recommended} />
                    <Carousel title={"Recommended"} movies={this.props.moviesRecon} />
                </div>

            </div>
        );
    }
}

const mapStateToProps = state => ({
    isLoading: state.app.isLoading,
    moviesRecon: state.app.moviesRecon
});

export default connect(mapStateToProps)(withRouter(MovieDetailPage));

对于第 29 行的 MovieDetailPage.js，我在控制台中记录了以下内容：

movie detail undefined 
{history: {…}, location: {…}, match: {…}, staticContext: undefined}
history: {length: 17, action: "PUSH", location: {…}, createHref: ƒ, push: ƒ, …}
location: {pathname: "/movie-detail", search: "?query=456740", hash: "", state: undefined, key: "dyth5r"}
match: {path: "/movie-detail", url: "/movie-detail", isExact: true, params: {…}}
staticContext: undefined
__proto__: Object

Reducers.js，如果需要，但我已经确认了操作，并且 Reducer 正确设置了状态，因为其他组件能够访问电影侦察。

const initialState = {
    isLoading: 0,
    genres: [],
    moviesPlaying: [],
    moviesPopular: [],
    moviesUpcoming: [],
    moviesTop: [],
    movieSearch:[],
    moviesRecon: [],
    searchTerm: ""

};

export const Reducer = (state=initialState, action) => {

    if (action.type === FETCH_RECON_SUCCESS) {
        return Object.assign({}, state, {
            moviesRecon: action.recon
        });
    }
}