时间戳

首页 > 解决方案 > 未处理的拒绝 (TypeError)：state.cartItems 未定义

javascript - 未处理的拒绝 (TypeError)：state.cartItems 未定义

问题描述

我正在关注 MERN STACK 教程，在设置我的购物车时这是我得到的错误，但是，我 console.log 在我的减速器中记录数据并且它正在显示但不知道为什么它会显示这个错误

Unhandled Rejection (TypeError): state.cartItems is undefined

还有，为什么导师是用localStorage来存储数据的，难道我们不能在获取Cart Action之后直接发给reducer吗……是怎么关联的？

谢谢你

购物车行动

import { ADD_TO_CART } from '../constants/CartConstants';
import axios from "axios";

export const addToCart = (id, qty) => async (dispatch, getState) => {

    const { data } = await axios.get(`/api/products/${id}`);

    dispatch({
        type: ADD_TO_CART,
        payload: {
            product: data._id,
            name: data.name,
            image: data.image,
            price: data.price,
            countInStock: data.countInStock,
            qty
        }

    })

    localStorage.setItem('cartItems', JSON.stringify(getState().cart.cartItems))

店铺

import {createStore , applyMiddleware, combineReducers} from 'redux';
import thunk from 'redux-thunk'
import {composeWithDevTools} from 'redux-devtools-extension';
import {productListReducer , productDetailsReducer } from './reducers/productReducer' ;
import {cartReducer} from "./reducers/cartReducer"

const reducer = combineReducers({
    productList: productListReducer,
    productDetails:productDetailsReducer,
    cart: cartReducer
});

const cartItemsFromStorage = localStorage.getItem('cartItems') ? JSON.parse(localStorage.getItem('cartItems')) : []

const initialState = {
    cart: cartItemsFromStorage
};

const middleware = [thunk];
const store = createStore(reducer , initialState ,   composeWithDevTools(applyMiddleware(...middleware)))

//composite with dev tools is used to connect our store with our devtools

export default store;

推车减速器

import { ADD_TO_CART } from '../constants/CartConstants';

export const cartReducer = (state = { cartItems: [] }, action) => {
    switch (action.type) {
        case ADD_TO_CART:
            const item = action.payload;
            const existItem = state.cartItems.find((x) => x.product === item.product)
            console.log(existItem)

            if (existItem) {
                return {
                    ...state,
                    cartItems: state.cartItems.map(x => x.product === existItem.product ? item : x)
                }
            } else {
                return {
                    ...state,
                    cartItems: [...state.cartItems, item]
                }
            }
        default:
            return state
    }
}

标签： javascriptreactjsreact-reduxfrontendmern

解决方案

确保这与您的状态结构相匹配

localStorage.setItem('cartItems', JSON.stringify(getState().*cart.cartItems*))

如果你命名不同，它可能会改变，例如

cartReducer.cartItems

推荐阅读