如何正确更新redux商店中的道具

Question

我有一个带有购物车组件的React应用程序。我使用Redux在点击"；添加到购物车"；按钮问题是，即使我更新了道具组件中的道具，道具也不会同时更新当我在Chrom开发者工具组件选项卡中检查组件中的道具时，只有当我导航到另一个组件时，我才能看到道具正在更新但是，购物车组件从未接收到用于填充购物车项目的更新道具这些是必要的组件。

项目组件

import React, { Component } from 'react';
import ProductData from './DataSet/ProductData';
import { compose } from 'recompose';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';
import { updateCartList } from '../../store/actions';
class LatestProducts extends Component {
addItemToCart = (id) => {
const { cartList, updateCartList } = this.props;
var items = cartList;
ProductData.forEach(each => {
if (each.id === id) {
items.push(each)
}
});
updateCartList(items);
}
render() {
return (
<div>
<div className="itemGridMain">
{
ProductData.map(product => {
return (
<div className="itemCard" key={product.id}>
<button onClick={() => this.addItemToCart(product.id)}>Add to cart</button>
</div>
)
})
}
</div>
</div>
);
}
}
function mapStateToProps(state) {
return {
cartList: state.cartList,
};
}
function mapDispatchToProps(dispatch) {
return bindActionCreators({
updateCartList: updateCartList,
}, dispatch);
}
export default compose(connect(mapStateToProps, mapDispatchToProps))(LatestProducts);

推车组件

import React, { Component } from 'react';
import { compose } from 'recompose';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';
import { updateCartList } from '../../store/actions';
class FrontHeader extends Component {
render() {
const { cartList } = this.props;
return (
<div className="cartList">
{
cartList && cartList.length > 0 && cartList.map(item => {
return (
<div className="listItem" key={item.id}>
</div>
)
})
}
</div>
);
}
}
function mapStateToProps(state) {
return {
cartList: state.cartList,
};
}
function mapDispatchToProps(dispatch) {
return bindActionCreators({
updateCartList: updateCartList,
}, dispatch);
}
export default compose(connect(mapStateToProps, mapDispatchToProps))(FrontHeader);

购物车列表缩减器

const cartListReducer = (state = [], action) => {
switch (action.type) {
case 'UPDATE_CARTLIST':
return action.payload;
default:
return state;
}
}
export default cartListReducer;

购物车列表索引

import cartListReducer from './cartlist';
import { combineReducers } from 'redux';
const allReducers = combineReducers({
cartList: cartListReducer,
})
export default allReducers;

Redux操作

export const updateCartList = (newCartList) => {
return {
type: 'UPDATE_CARTLIST',
payload: newCartList,
}
}

我该如何解决这个问题？

Answer 1

问题

this.props.cartList是您的状态，通过推入该数组并将其保存回状态，您只是在改变状态。

addItemToCart = (id) => {
const { cartList, updateCartList } = this.props;
var items = cartList; // <-- state reference
ProductData.forEach(each => {
if (each.id === id) {
items.push(each) // <-- push into state reference
}
});
updateCartList(items); // <-- saved state reference
}

解决方案

您应该为react提供一个新的数组对象引用来获取差异，因为协调使用浅层对象相等。

您的addItemToCart可能只需要将您想要添加到购物车中的项目，并将购物车更新逻辑移动到reducer中。

最新产品

class LatestProducts extends Component {
addItemToCart = (item) => {
const { updateCartList } = this.props;
updateCartList(item); // <-- pass item to action creator
}
render() {
return (
<div>
<div className="itemGridMain">
{ProductData.map(product => {
return (
<div className="itemCard" key={product.id}>
<button
onClick={() => this.addItemToCart(product)} // <-- pass product/item
>
Add to cart
</button>
</div>)
})
}
</div>
</div>
);
}
}

cartListReducer

const cartListReducer = (state = [], action) => {
switch (action.type) {
case 'UPDATE_CARTLIST':
return [...state, action.payload]; // <-- copy state and appen new item
default:
return state;
}
}