React redux 未从 API 获取数据

Question

Hi im new to redux and im trying to create a movie app using the API from www.themoviedb.org . I am trying to display the popular movies and im sure the API link works since ive tested it in postman but i cant seem to figure out why redux doesnt pick up the data.

//action
import { FETCH_POPULAR } from "./types";
import axios from "axios";

export const fetchPopularMovies = () => (dispatch) => {
  axios
    .get(
      `https://api.themoviedb.org/3/movie/popular?api_key=${API}&language=en-US`
    )
    .then((response) =>
      dispatch({
        type: FETCH_POPULAR,
        payload: response.data
      })
    )
    .catch((err) => console.log(err));
};

---

//reducer
import { FETCH_POPULAR } from "../actions/types";

const initialState = {
  popular: [],
};

export default function (state = initialState, action) {
  switch (action.type) {
    case FETCH_POPULAR:
      return {
        ...state,
        popular: action.payload,
      };
    default:
      return state;
  }
}

---

import React from "react";
import { connect } from "react-redux";
import Popular from "./Popular";


const FetchedPopular = (props) => {
  const { popular } = props;
  let content = "";

  content =
    popular.length > 0
      ? popular.map((item, index) => (
          <Popular key={index} popular={item} />
        
        ))
      : null;

  return <div className="fetched-movies">{content}</div>;
};

const mapStateToProps = (state) => ({
  popular: state.popular.popular,
});

export default connect(mapStateToProps)(FetchedPopular);

---

import React from "react";
import "../Styles.css";

const Popular = (props) => {
  return (
    <div className="movie-container">
      <img
        className="poster"
        src={`https://image.tmdb.org/t/p/w400/${props.poster_path}`}
      />
      
    </div>
  );
};

export default Popular;

I cant really tell what I'm missing can someone help?

Answer 1

Next to mapStateToProps you need to create mapDispatchToProps . After that, you will be able to call your Redux action from your React component. I suggest you the mapDispatchToProps as an Object form. Then you need to use this mapDispatchToProps as the second parameter of your connect method.

When you will have your action mapped to your component, you need to call it somewhere. It is recommended to do it for example on a component mount. As your React components are Functional components, you need to do it in React useEffect hook .

import React, { useEffect } from "react";
import { connect } from "react-redux";
import Popular from "./Popular";
import { fetchPopularMovies } from 'path_to_your_actions_file'

const FetchedPopular = (props) => {
  const { popular } = props;
  let content = "";

  useEffect(()=> {
    // call your mapped action (here it is called once on component mount due the empty dependency array of useEffect hook)
    props.fetchPopularMovies();
  }, [])

  content =
    popular.length > 0
      ? popular.map((item, index) => (
          <Popular key={index} popular={item} />
        
        ))
      : null;

  return <div className="fetched-movies">{content}</div>;
};

const mapStateToProps = (state) => ({
  popular: state.popular.popular,
});

// create mapDispatchToProps
const mapDispatchToProps = {
  fetchPopularMovies
}

// use mapDispatchToProps as the second parameter of your `connect` method.
export default connect(mapStateToProps, mapDispatchToProps)(FetchedPopular);

Moreover, as I wrote above in my comment, your Popular does not have the prop poster_path but it has the prop popular which probably has the property poster_path .

import React from "react";
import "../Styles.css";

const Popular = (props) => {
  return (
    <div className="movie-container">
      <img
        className="poster"
        src={`https://image.tmdb.org/t/p/w400/${props.popular.poster_path}`}
      />
      
    </div>
  );
};

export default Popular;