前端數(shù)據(jù)流之Redux篇（案例）

create-react-app cart
npm i redux react-redux redux-thunk

結(jié)構(gòu)如下

頁面結(jié)構(gòu)圖
代碼如下

acions > index.js

import * as shop from '../api/shop'

export const reciveProducts = products => ({
  type: 'RECIVE_PRODUCTS',
  products
})
export const addToCart = product => ({
  type: 'ADD_TO_CART',
  product
})
export const getAllProducts = () => dispatch => {
  shop.getAllProducts(products => {
    dispatch(reciveProducts(products))
  })
}

export const setCheckoutStatus = status => ({
  type: 'SET_CHECKOUT_STATUS',
  status
})
export const setCarItems = items => ({
  type: 'SET_ITEMS',
  items
})
export const checkout = (products) => dispatch => {
  // 1.備份購物車數(shù)據(jù)羹与，結(jié)算失敗好返回
  const tempCartPro = [...products]
  // 2.清空結(jié)算狀態(tài)
  dispatch(setCheckoutStatus(null))
  // 3.清空購物車
  dispatch(setCarItems([]))
  // 4.執(zhí)行結(jié)算操作
  shop.buyProducts(
    products,
    // 成功
    () => dispatch(setCheckoutStatus('success')),
    // 失敗
    () => {
      dispatch(setCheckoutStatus('fail'))
      dispatch(setCarItems(tempCartPro))
    }
  )
}

api > shop.js

const _products = [
  {"id": 1, "title": "9.9包郵華為手機(jī)", "price": 9.9, "inventory": 3},
  {"id": 2, "title": "樂高積木馬里奧超級馬里奧周邊", "price": 1119.9, "inventory": 12},
  {"id": 3, "title": "ps4荒野大鏢客不好玩免單", "price": 229.9, "inventory": 5},
]
// 模擬接口
export const getAllProducts = callback => {
  setTimeout(() => {
    callback(_products)
  }, 1000);
}
export const buyProducts = (products, callback, errCallback) => {
  setTimeout(() => {
    Math.random() > 0.5 ? callback() : errCallback()
  }, 500);
}

components > Cart.js

import React, { Component } from 'react'

class Cart extends Component {
  render() {
    const {cartProducts, totalPrice, checkout, checkoutStatus} = this.props
    return (
      <div>
        <h2>Cart</h2>
        <ul>
          {cartProducts.map(item => (
            <li key={item.id}>
              {item.title}-{item.price}-{item.quantity}
            </li>
          ))}
        </ul>
        {!cartProducts.length && <p>請?zhí)砑由唐返劫徫镘?lt;/p>}
        <div>總價格是：{totalPrice}</div>
        <br/>
        <button
        disabled={!cartProducts.length}
        onClick={() => checkout(cartProducts)}>
          結(jié)算
        </button>
        <br/>
        {checkoutStatus && <div>結(jié)算信息{checkoutStatus}</div>}
      </div>
    )
  }
}

export default Cart

components > Products.js

import React, { Component } from 'react'

class Products extends Component {
  render() {
    const { products } = this.props
    return (
      <div>
        <h2>products</h2>
        <ul>
          {products.map(item => (
            <li key={item.id}>
              {item.title}-{item.price}-{item.inventory}
              <br />
              <button
                disabled={!item.inventory}
                onClick={() => this.props.addToCart(item)}>
                {item.inventory ? '添加到購物車' : '庫存為0'}
              </button>
            </li>
          ))}
        </ul>
      </div>
    )
  }
  componentDidMount() {
    this.props.getAllProducts()
  }
}

export default Products

container > CartContainer.js

import { connect } from 'react-redux'
import Cart from '../components/Cart'
import {checkout} from '../actions'

// 將products中的數(shù)據(jù)映射到cart中來
const getCartProducts = state => {
  return state.cart.items.map( cartItem => {
    const product = state.products.all.find(proItem => proItem.id === cartItem.id)
    return {
      id: product.id,
      title: product.title,
      price: product.price,
      quantity: cartItem.quantity
    }
  })
}
// 獲取總價
const getTotalPrice = state => {
  return getCartProducts(state).reduce((total, product) => {
    return total + product.price * product.quantity
  }, 0) 
}

const mapStateToProps = state => {
  return {
    cartProducts: getCartProducts(state),
    totalPrice: getTotalPrice(state),
    checkoutStatus: state.cart.checkoutStatus
  }
}

const mapDispatchToProps = {
    checkout
}

const CartContainer = connect(
  mapStateToProps,
  mapDispatchToProps
) (Cart)

export default CartContainer

container > ProductsContainer.js

import { connect } from 'react-redux'
import Products from '../components/Products'
import { getAllProducts, addToCart } from '../actions'

const mapStateToProps = state => {
  return {
    products: state.products.all
  }
}

const mapDispatchToProps = {
  getAllProducts,
  addToCart
}

const ProductsContainer = connect(
  mapStateToProps,
  mapDispatchToProps
) (Products)

export default ProductsContainer

reducers > cart.js

const initialState = {
  items: [],
  checkoutStatus: null
}
const items = (state = initialState.items, action) => {
  switch (action.type) {
    case 'ADD_TO_CART':
      // 判斷購物車存在商品嗎
      // 存在 - quantity+1
      // 不存在 - 添加商品到購物車
      const productId = action.product.id
      const product = state.find(item => item.id === productId)
      if (product) {
        product.quantity++
        return [...state]
      } else {
        return [...state, {
          id: productId,
          quantity: 1
        }]
      }
    case 'SET_ITEMS':
      return action.items
    default:
      return state
  }
}
const checkoutStatus = (state = initialState.checkoutStatus, action) => {
  switch (action.type) {
    case 'SET_CHECKOUT_STATUS':
      return action.status
    default:
      return state
    }
}
export default (state = initialState, action) => {
  return {
    items: items(state.items, action),
    checkoutStatus: checkoutStatus(state.checkoutStatus, action)
  }
}

reducers > products.js

const initialState = {
  all: []
}
const all = (state = initialState.all, action) => {
  switch (action.type) {
    case 'RECIVE_PRODUCTS':
      return action.products
    case 'ADD_TO_CART':
      const productId = action.product.id
      const product = state.find(item => item.id === productId)
      product.inventory--
      return [...state]
    default:
      return state
  }
}

export default (state = initialState, action) => {
  return {
    all: all(state.all, action),
  }
}

store > index.js

import { createStore, combineReducers, applyMiddleware, compose  } from 'redux'
import thunk from 'redux-thunk'
import products from '../reducers/products'
import cart from '../reducers/cart'

const rootReducer = combineReducers({
  products,
  cart
})
const composeEnhancers =
  window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ ?
  window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__({}) : compose;

const enhancer = composeEnhancers(
  applyMiddleware(thunk)
)

const store = createStore(
  rootReducer,
  // 啟用redux調(diào)試工具
  enhancer
)
export default store

優(yōu)化與建議
action.type里面的值是字符串恒傻，這樣每次使用dispatch的時候荆忍，輸入的參數(shù)是字符串凰慈，容易出錯汛蝙。
解決辦法：
定義一個公用文件省咨，把action.type保存進(jìn)去吼肥，每次使用的時候乌叶，將字符串的部分替換成對應(yīng)的變量即可跷敬。