示例：Reddit API

这是一个高级教程的例子，包含使用 Reddit API 请求文章标题的全部源码。

入口

index.js

import 'babel-polyfill'
import React from 'react'
import { render } from 'react-dom'
import Root from './containers/Root'
render(
  <Root />,
  document.getElementById('root')
)

Action Creators 和 Constants

actions.js

import fetch from 'cross-fetch'
export const REQUEST_POSTS = 'REQUEST_POSTS'
export const RECEIVE_POSTS = 'RECEIVE_POSTS'
export const SELECT_SUBREDDIT = 'SELECT_SUBREDDIT'
export const INVALIDATE_SUBREDDIT = 'INVALIDATE_SUBREDDIT'
export function selectSubreddit(subreddit) {
  return {
    type: SELECT_SUBREDDIT,
    subreddit
  }
}
export function invalidateSubreddit(subreddit) {
  return {
    type: INVALIDATE_SUBREDDIT,
    subreddit
  }
}
function requestPosts(subreddit) {
  return {
    type: REQUEST_POSTS,
    subreddit
  }
}
function receivePosts(subreddit, json) {
  return {
    type: RECEIVE_POSTS,
    subreddit,
    posts: json.data.children.map(child => child.data),
    receivedAt: Date.now()
  }
}
function fetchPosts(subreddit) {
  return dispatch => {
    dispatch(requestPosts(subreddit))
    return fetch(`https://www.reddit.com/r/${subreddit}.json`)
      .then(response => response.json())
      .then(json => dispatch(receivePosts(subreddit, json)))
  }
}
function shouldFetchPosts(state, subreddit) {
  const posts = state.postsBySubreddit[subreddit]
  if (!posts) {
    return true
  } else if (posts.isFetching) {
    return false
  } else {
    return posts.didInvalidate
  }
}
export function fetchPostsIfNeeded(subreddit) {
  return (dispatch, getState) => {
    if (shouldFetchPosts(getState(), subreddit)) {
      return dispatch(fetchPosts(subreddit))
    }
  }
}

Reducers

reducers.js

import { combineReducers } from 'redux'
import {
  SELECT_SUBREDDIT,
  INVALIDATE_SUBREDDIT,
  REQUEST_POSTS,
  RECEIVE_POSTS
} from './actions'
function selectedSubreddit(state = 'reactjs', action) {
  switch (action.type) {
  case SELECT_SUBREDDIT:
    return action.subreddit
  default:
    return state
  }
}
function posts(
  state = {
    isFetching: false,
    didInvalidate: false,
    items: []
  },
  action
) {
  switch (action.type) {
    case INVALIDATE_SUBREDDIT:
      return Object.assign({}, state, {
        didInvalidate: true
      })
    case REQUEST_POSTS:
      return Object.assign({}, state, {
        isFetching: true,
        didInvalidate: false
      })
    case RECEIVE_POSTS:
      return Object.assign({}, state, {
        isFetching: false,
        didInvalidate: false,
        items: action.posts,
        lastUpdated: action.receivedAt
      })
    default:
      return state
  }
}
function postsBySubreddit(state = {}, action) {
  switch (action.type) {
    case INVALIDATE_SUBREDDIT:
    case RECEIVE_POSTS:
    case REQUEST_POSTS:
      return Object.assign({}, state, {
        [action.subreddit]: posts(state[action.subreddit], action)
      })
    default:
      return state
  }
}
const rootReducer = combineReducers({
  postsBySubreddit,
  selectedSubreddit
})
export default rootReducer

Store

configureStore.js

import { createStore, applyMiddleware } from 'redux'
import thunkMiddleware from 'redux-thunk'
import { createLogger } from 'redux-logger'
import rootReducer from './reducers'
const loggerMiddleware = createLogger()
export default function configureStore(preloadedState) {
  return createStore(
    rootReducer,
    preloadedState,
    applyMiddleware(
      thunkMiddleware,
      loggerMiddleware
    )
  )
}

容器型组件

containers/Root.js

import React, { Component } from 'react'
import { Provider } from 'react-redux'
import configureStore from '../configureStore'
import AsyncApp from './AsyncApp'
const store = configureStore()
export default class Root extends Component {
  render() {
    return (
      <Provider store={store}>
        <AsyncApp />
      </Provider>
    )
  }
}

containers/AsyncApp.js

import React, { Component } from 'react'
import PropTypes from 'prop-types'
import { connect } from 'react-redux'
import {
  selectSubreddit,
  fetchPostsIfNeeded,
  invalidateSubreddit
} from '../actions'
import Picker from '../components/Picker'
import Posts from '../components/Posts'
class AsyncApp extends Component {
  constructor(props) {
    super(props)
    this.handleChange = this.handleChange.bind(this)
    this.handleRefreshClick = this.handleRefreshClick.bind(this)
  }
  componentDidMount() {
    const { dispatch, selectedSubreddit } = this.props
    dispatch(fetchPostsIfNeeded(selectedSubreddit))
  }
  componentWillReceiveProps(nextProps) {
    if (nextProps.selectedSubreddit !== this.props.selectedSubreddit) {
      const { dispatch, selectedSubreddit } = nextProps
      dispatch(fetchPostsIfNeeded(selectedSubreddit))
    }
  }
  handleChange(nextSubreddit) {
    this.props.dispatch(selectSubreddit(nextSubreddit))
  }
  handleRefreshClick(e) {
    e.preventDefault()
    const { dispatch, selectedSubreddit } = this.props
    dispatch(invalidateSubreddit(selectedSubreddit))
    dispatch(fetchPostsIfNeeded(selectedSubreddit))
  }
  render() {
    const { selectedSubreddit, posts, isFetching, lastUpdated } = this.props
    return (
      <div>
        <Picker value={selectedSubreddit}
                onChange={this.handleChange}
                options={[ 'reactjs', 'frontend' ]} />
        <p>
          {lastUpdated &&
            <span>
              Last updated at {new Date(lastUpdated).toLocaleTimeString()}.
              {' '}
            </span>
          }
          {!isFetching &&
            <a href='#'
               onClick={this.handleRefreshClick}>
              Refresh
            </a>
          }
        </p>
        {isFetching && posts.length === 0 &&
          <h2>Loading...</h2>
        }
        {!isFetching && posts.length === 0 &&
          <h2>Empty.</h2>
        }
        {posts.length > 0 &&
          <div style={{ opacity: isFetching ? 0.5 : 1 }}>
            <Posts posts={posts} />
          </div>
        }
      </div>
    )
  }
}
AsyncApp.propTypes = {
  selectedSubreddit: PropTypes.string.isRequired,
  posts: PropTypes.array.isRequired,
  isFetching: PropTypes.bool.isRequired,
  lastUpdated: PropTypes.number,
  dispatch: PropTypes.func.isRequired
}
function mapStateToProps(state) {
  const { selectedSubreddit, postsBySubreddit } = state
  const {
    isFetching,
    lastUpdated,
    items: posts
  } = postsBySubreddit[selectedSubreddit] || {
    isFetching: true,
    items: []
  }
  return {
    selectedSubreddit,
    posts,
    isFetching,
    lastUpdated
  }
}
export default connect(mapStateToProps)(AsyncApp)

展示型组件

components/Picker.js

import React, { Component } from 'react'
import PropTypes from 'prop-types'
export default class Picker extends Component {
  render() {
    const { value, onChange, options } = this.props
    return (
      <span>
        <h1>{value}</h1>
        <select onChange={e => onChange(e.target.value)}
                value={value}>
          {options.map(option =>
            <option value={option} key={option}>
              {option}
            </option>)
          }
        </select>
      </span>
    )
  }
}
Picker.propTypes = {
  options: PropTypes.arrayOf(
    PropTypes.string.isRequired
  ).isRequired,
  value: PropTypes.string.isRequired,
  onChange: PropTypes.func.isRequired
}

components/Posts.js

import React, { Component } from 'react'
import PropTypes from 'prop-types'
export default class Posts extends Component {
  render() {
    return (
      <ul>
        {this.props.posts.map((post, i) =>
          <li key={i}>{post.title}</li>
        )}
      </ul>
    )
  }
}
Posts.propTypes = {
  posts: PropTypes.array.isRequired
}