javascript - Redux 无法读取未定义的属性 'payload'

Question

我正在使用 Redux 和 React 从 API 加载数据。尽管成功提取数据并将其应用到状态，但它会抛出错误:

Uncaught TypeError: Cannot read property 'payload' of undefined.

这发生在控制台中的 FETCH_PRODUCT_LISTINGS_PENDING 操作类型之后。

react 组件:

import React from 'react';
import { connect } from 'react-redux';
import store from '../../../store';

import * as ProductListingActions from '../actions/ProductListingActions';

@connect((store) => {
    return {
        productListing: store.productListing.products
    }
})

export default class ProductListingContainer extends React.Component {
    constructor(data) {
        super();
        this.props = data;
        this.props.dispatch(ProductListingActions.fetchProductListings());
    }
    render() {
        return <div></div>;
    }
}

reducer :

import CookieHandler from '../../../modules/CookieHandler';
const cookieHandler = new CookieHandler;

export default function reducer(
    state = {
        products: [],
        fetching: false,
        fetched: false,
        error: null
    }, action) {

    switch(action.type) {
        case "FETCH_PRODUCT_LISTINGS_PENDING":
            return {
                ...state,
                fetching: true,
            }
            break;
        case "FETCH_PRODUCT_LISTINGS_REJECTED":
            return {
                ...state,
                fetching: false,
                error: action.payload
            }
            break;
        case "FETCH_PRODUCT_LISTINGS_FULFILLED":
            return {
                ...state,
                fetching: false,
                fetched: true,
                products: action.payload.data.default
            }
            break;
    }

    return state;
}

操作:

import Config from '../../../Config.js';
import store from '../../../store.js';
import axios from 'axios';

export function fetchProductListings() {
    store.dispatch({
        type: "FETCH_PRODUCT_LISTINGS",
        payload: axios.get(Config.getConfigAPIUrl() + '/cartel/products')
    })

}

如有任何帮助，我们将不胜感激

Answer 1

您正在调度对调度的调用，而不是调度对象。

this.props.dispatch(ProductListingActions.fetchProductListings());

function fetchProductListings() {
  store.dispatch({
    type: "FETCH_PRODUCT_LISTINGS",
    payload: axios.get(Config.getConfigAPIUrl() + '/cartel/products')
  })
}

如果你内联这个:

this.props.dispatch(
  store.dispatch({
    type: "FETCH_PRODUCT_LISTINGS",
    payload: axios.get(Config.getConfigAPIUrl() + '/cartel/products')
  })
)

你的 Action 创建者不应该调用调度，它应该只返回一个 Action :

export function fetchProductListings() {
  return {
    type: "FETCH_PRODUCT_LISTINGS",
    payload: axios.get(Config.getConfigAPIUrl() + '/cartel/products')
  }
}

但请记住，axios.get 是异步的，因此 payload 将是 promise 。您可能需要考虑添加 redux-thunk 来处理 promise 的履行。