React Redux 从后端方法获取数据

IT技术 reactjs redux redux-thunk
2021-04-08 14:48:50

我有点困惑,希望得到一个能帮助我理清思路的答案。假设我有一个后端(nodejs、express 等),我在其中存储我的用户及其数据,有时我想从后端获取数据,例如登录后的用户信息,或产品列表并保存他们在状态。

到目前为止,我的方法和我所看到的,我在组件加载之前获取数据并使用响应中的数据分派一个动作。但我最近开始深入研究这个,我看到了我之前知道的 react-thunk 库,并开始想知道从后端/API 获取的最佳实践是什么?React Hooks 对这个话题有什么改变吗?知道这一点很重要吗?

我觉得有点傻,但找不到完全谈论这个话题的文章或视频:)

1个回答

要执行此最佳实践,请使用以下方法:

我使用了一些包和模式以获得最佳实践:

  • redux-logger用于在浏览器控制台中记录操作和状态。
  • reselect选择器可以计算派生数据,允许 Redux 存储最小可能的状态等。
  • redux-thunk Thunk 是基本 Redux 副作用逻辑的推荐中间件,包括需要访问存储的复杂同步逻辑,以及简单的异步逻辑,如 AJAX 请求等。
  • axios用于 api(用于浏览器和 node.js 的基于 Promise 的 HTTP 客户端)

通过创建名称的目录终极版或像你的任何名称src文件夹,然后创建两个文件store.js,并rootReducer.js在终极版目录。我们假设从 API 获取产品。

去做这个:

通过创建名称的新目录的产品在终极版目录中,然后通过名称创建四个文件product.types.js, product.actions.js, product.reducer.js, product.selector.jsredux/product目录

项目的结构应该如下

...
src
  App.js
  redux
    product
      product.types.js
      product.actions.js
      product.reducer.js
    rootReducer.js
    store.js
 Index.js
package.json
...

商店.js

在这个文件中我们进行了 redux 配置

// redux/store.js:
import { createStore, applyMiddleware } from "redux";
import logger from "redux-logger";
import thunk from "redux-thunk";

import rootReducer from "./root-reducer";

const middlewares = [logger, thunk];

export const store = createStore(rootReducer, applyMiddleware(...middlewares));

rootReducer.js

combineReducers辅助函数变成一个对象,其值是不同的减少功能为可以传递到单个减小功能createStore

// redux/rootReducer.js
import { combineReducers } from "redux";

import productReducer from "./product/product.reducer";

const rootReducer = combineReducers({
  shop: productReducer,
});

export default rootReducer;

product.types.js 在这个文件中,我们定义了用于管理操作类型的常量。

export const ShopActionTypes = {
  FETCH_PRODUCTS_START: "FETCH_PRODUCTS_START",
  FETCH_PRODUCTS_SUCCESS: "FETCH_PRODUCTS_SUCCESS",
  FETCH_PRODUCTS_FAILURE: "FETCH_PRODUCTS_FAILURE"
};

product.actions.js 在这个文件中,我们为处理动作创建动作创建器。

// redux/product/product.actions.js
import { ShopActionTypes } from "./product.types";
import axios from "axios";

export const fetchProductsStart = () => ({
  type: ShopActionTypes.FETCH_PRODUCTS_START
});

export const fetchProductsSuccess = products => ({
  type: ShopActionTypes.FETCH_PRODUCTS_SUCCESS,
  payload: products
});

export const fetchProductsFailure = error => ({
  type: ShopActionTypes.FETCH_PRODUCTS_FAILURE,
  payload: error
});

export const fetchProductsStartAsync = () => {
  return dispatch => {
    dispatch(fetchProductsStart());
    axios
      .get(url)
      .then(response => dispatch(fetchProductsSuccess(response.data.data)))
      .catch(error => dispatch(fetchProductsFailure(error)));
  };
};

product.reducer.js 在这个文件中,我们创建productReducer了处理动作的函数。

import { ShopActionTypes } from "./product.types";

const INITIAL_STATE = {
  products: [],
  isFetching: false,
  errorMessage: undefined,
};

const productReducer = (state = INITIAL_STATE, action) => {
  switch (action.type) {
    case ShopActionTypes.FETCH_PRODUCTS_START:
      return {
        ...state,
        isFetching: true
      };
    case ShopActionTypes.FETCH_PRODUCTS_SUCCESS:
      return {
        ...state,
        products: action.payload,
        isFetching: false
      };
    case ShopActionTypes.FETCH_PRODUCTS_FAILURE:
      return {
        ...state,
        isFetching: false,
        errorMessage: action.payload
      };
    default:
      return state;
  }
};

export default productReducer;

product.selector.js 在这个文件中,我们选择productsisFetching从商店状态。

import { createSelector } from "reselect";

const selectShop = state => state.shop;

export const selectProducts = createSelector(
  [selectShop],
  shop => shop.products
);

export const selectIsProductsFetching = createSelector(
  [selectShop],
  shop => shop.isFetching
);

Index.js 在这个文件中包装了整个应用程序和组件,Provider用于访问存储和状态的子组件。

// src/Index.js
import React from "react";
import ReactDOM from "react-dom";
import App from "./App";

import { Provider } from "react-redux";
import { store } from "./redux/store";

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById("root")
);

App.js 类组件 在这个文件中,我们使用类组件连接到商店和状态

// src/App.js
import React, { Component } from "react";

import { connect } from "react-redux";
import { createStructuredSelector } from "reselect";
import {
  selectIsProductsFetching,
  selectProducts
} from "./redux/product/product.selectors";

import { fetchProductsStartAsync } from "./redux/product/product.actions";

class App extends Component {
  componentDidMount() {
    const { fetchProductsStartAsync } = this.props;
    fetchProductsStartAsync();
  }

  render() {
    const { products, isProductsFetching } = this.props;
    console.log('products', products);
    console.log('isProductsFetching', isProductsFetching);
    return (
      <div className="App">Please see console in browser</div>
    );
  }
}

const mapStateToProps = createStructuredSelector({
  products: selectProducts,
  isProductsFetching: selectIsProductsFetching,
});

const mapDispatchToProps = dispatch => ({
  fetchProductsStartAsync: () => dispatch(fetchProductsStartAsync())
});

export default connect(
  mapStateToProps,
  mapDispatchToProps
)(App);

或带有功能组件( useEffect 钩子)的 App.js 在这个文件中,我们确实连接到带有功能组件的商店和状态

// src/App.js
import React, { Component, useEffect } from "react";

import { connect } from "react-redux";
import { createStructuredSelector } from "reselect";
import {
  selectIsProductsFetching,
  selectProducts
} from "./redux/product/product.selectors";

import { fetchProductsStartAsync } from "./redux/product/product.actions";

const App = ({ fetchProductsStartAsync, products, isProductsFetching}) => {
  useEffect(() => {
    fetchProductsStartAsync();
  },[]);

    console.log('products', products);
    console.log('isProductsFetching', isProductsFetching);

    return (
      <div className="App">Please see console in browser</div>
    );
}

const mapStateToProps = createStructuredSelector({
  products: selectProducts,
  isProductsFetching: selectIsProductsFetching,
});

const mapDispatchToProps = dispatch => ({
  fetchProductsStartAsync: () => dispatch(fetchProductsStartAsync())
});

export default connect(
  mapStateToProps,
  mapDispatchToProps
)(App);
别客气。如果有帮助,请勾选投票旁边的绿色标记。祝你好运。
2021-06-03 14:48:50
谢谢!!终于有一个完整的例子和解释,它帮了我很多:)
2021-06-14 14:48:50