如何正确地从 ReactJS + Redux 应用程序进行 REST 调用？

Question

我正在使用 ReactJS + Redux，以及 Express 和 Webpack。构建了一个 API，我希望能够从客户端进行 REST 调用——GET、POST、PUT、DELETE。

使用 Redux 架构如何以及正确的方法是什么？在 reducer、action creators、store 和 react 路由方面，任何好的流程示例都会非常有帮助。

提前谢谢你！

Answer 1

最简单的方法是使用redux-thunk 包。这个包是一个 redux 中间件，所以首先你应该把它连接到 redux：

import { createStore, applyMiddleware } from 'redux';
import thunk from 'redux-thunk';
import rootReducer from './reducers/index';

const store = createStore(
  rootReducer,
  applyMiddleware(thunk)
);

这允许您调度 async 操作以及常规 sync 操作。让我们创建一个：

// actions.js

export function fetchTodos() {
  // Instead of plain objects, we are returning function.
  return function(dispatch) {
    // Dispatching REQUEST action, which tells our app, that we are started requesting todos.
    dispatch({
      type: 'FETCH_TODOS_REQUEST'
    });
    return fetch('/api/todos')
      // Here, we are getting json body(in our case it will contain `todos` or `error` prop, depending on request was failed or not) from server response
      // And providing `response` and `body` variables to the next chain.
      .then(response => response.json().then(body => ({ response, body })))
      .then(({ response, body }) => {
        if (!response.ok) {
          // If request was failed, dispatching FAILURE action.
          dispatch({
            type: 'FETCH_TODOS_FAILURE',
            error: body.error
          });
        } else {
          // When everything is ok, dispatching SUCCESS action.
          dispatch({
            type: 'FETCH_TODOS_SUCCESS',
            todos: body.todos
          });
        }
      });
  }
}

我更喜欢将 React 组件与展示组件和容器组件分开。这种方法在this article 中得到了完美的描述。

接下来，我们应该创建TodosContainer 组件，该组件将为展示性Todos 组件提供数据。在这里，我们使用react-redux 库：

// TodosContainer.js

import React, { Component } from 'react';
import { connect } from 'react-redux';
import { fetchTodos } from '../actions';

class TodosContainer extends Component {
  componentDidMount() {
    // When container was mounted, we need to start fetching todos.
    this.props.fetchTodos();
  }

  render() {
    // In some simple cases, it is not necessary to create separate `Todos` component. You can put todos markup directly here.
    return <Todos items={this.props.todos} />
  }
}

// This function is used to convert redux global state to desired props.
function mapStateToProps(state) {
  // `state` variable contains whole redux state.
  return {
    // I assume, you have `todos` state variable.
    // Todos will be available in container component as `this.props.todos`
    todos: state.todos
  };
}

// This function is used to provide callbacks to container component.
function mapDispatchToProps(dispatch) {
  return {
    // This function will be available in component as `this.props.fetchTodos`
    fetchTodos: function() {
      dispatch(fetchTodos());
    }
  };
}

// We are using `connect` function to wrap our component with special component, which will provide to container all needed data.
export default connect(mapStateToProps, mapDispatchToProps)(TodosContainer);

此外，您应该创建todosReducer，它将处理FETCH_TODOS_SUCCESS 操作，如果您想显示加载程序/错误消息，还应处理其他 2 个操作。

// reducers.js

import { combineReducers } from 'redux';

const INITIAL_STATE = {
  items: [],
  isFetching: false,
  error: undefined
};

function todosReducer(state = INITIAL_STATE, action) {
  switch (action.type) {
    case 'FETCH_TODOS_REQUEST':
      // This time, you may want to display loader in the UI.
      return Object.assign({}, state, {
        isFetching: true
      });
    case 'FETCH_TODOS_SUCCESS':
      // Adding derived todos to state
      return Object.assign({}, state, {
        isFetching: false,
        todos: action.todos
      });
    case 'FETCH_TODOS_FAILURE':
      // Providing error message to state, to be able display it in UI.
      return Object.assign({}, state, {
        isFetching: false,
        error: action.error
      });
    default:
      return state;
  }
}

export default combineReducers({
  todos: todosReducer
});

对于CREATE、UPDATE、DELETE 等其他操作没有什么特别之处，它们的实现方式相同。

Answer 2

简短的回答是：

1. redux 不是架构
2. 您可以使用任何库。现在很多人直接使用 fetch API。
3. 为了能够将 redux 与异步操作（AJAX 需要）集成，您需要使用库来提供帮助。正如其他人所说，最受欢迎的两个是 redux-thunk 和 redux-saga。

对于可以放入您的 redux 应用程序的脑死简单库，您可以尝试redux-crud-store。免责声明：我写的。如果您有兴趣将 fetch API 或其他 API 客户端与 redux-saga 集成，您还可以阅读 redux-crud-store 的源代码

Answer 3

这是 redux-thunk、redux-saga 和 redux-observable 等库的主要用例。

redux-thunk 是最简单的，你可以这样做：

import fetch from 'isomorphic-fetch'

export const REQUEST_POSTS = 'REQUEST_POSTS'
function requestPosts(subreddit) {
  return {
    type: REQUEST_POSTS,
    subreddit
  }
}

export const RECEIVE_POSTS = 'RECEIVE_POSTS'
function receivePosts(subreddit, json) {
  return {
    type: RECEIVE_POSTS,
    subreddit,
    posts: json.data.children.map(child => child.data),
    receivedAt: Date.now()
  }
}

// Meet our first thunk action creator!
// Though its insides are different, you would use it just like any other action creator:
// store.dispatch(fetchPosts('reactjs'))

export function fetchPosts(subreddit) {

  // Thunk middleware knows how to handle functions.
  // It passes the dispatch method as an argument to the function,
  // thus making it able to dispatch actions itself.

  return function (dispatch) {

    // First dispatch: the app state is updated to inform
    // that the API call is starting.

    dispatch(requestPosts(subreddit))

    // The function called by the thunk middleware can return a value,
    // that is passed on as the return value of the dispatch method.

    // In this case, we return a promise to wait for.
    // This is not required by thunk middleware, but it is convenient for us.

    return fetch(`http://www.reddit.com/r/${subreddit}.json`)
      .then(response => response.json())
      .then(json =>

        // We can dispatch many times!
        // Here, we update the app state with the results of the API call.

        dispatch(receivePosts(subreddit, json))
      )

      // In a real world app, you also want to
      // catch any error in the network call.
  }
}

以上示例直接取自http://redux.js.org/docs/advanced/AsyncActions.html，这确实是您问题答案的权威来源。