react-refetch的使用小例子

出處：《react設計模式和最佳實踐》
作者：米凱萊·貝爾託利
出版時間：2018年8月第1版（還算新）

使用react-refetch來簡化api獲取數據的代碼

const List = ({data: gists}) => {
  return (
    <ul>
      {gists.map(gist => (
        <li key={gist.id}>{gist.description}</li>
      ))}
    </ul>
  )
}

const withData = url => Part => {
  return class extends Component {
    state = {data: []}

    componentDidMount() {
      fetch(url)
        .then(response => response.json ? response.json() : response)
        .then(data => this.setState({data}))
    }

    render() {
      return <Part {...this.state} {...this.props} />
    }
  }
}

const ListWithGists = withData('https://api.github.com/users/gaearon/gists')(List)

上面的代碼，我們將api獲取數據的邏輯用高階組件抽離出來，下面我們再用react-refetch來簡化上面的異步代碼

import { connect as refetchConnect } from 'react-refetch'

const List = ({gists}) => {
  if (gists.pending) {
    return <div>loading...</div>
  } else if (gists.rejected) {
    return <div>{gists.reason}</div>
  } else if (gists.fulfilled) {
    return (
      gists.fulfilled && <ul>
        {gists.value.map(gist => (
          <li key={gist.id}>{gist.description}</li>
        ))}
      </ul>
    )
  }
}

const ListWithGists = refetchConnect(() => ({gists: `https://api.github.com/users/gaearon/gists`}))(List)

瞬間清爽多了，順便利用react-refetch提供的屬性，順便把loading邏輯也添加了

分離列表和項目的職責

很明顯，List組件是一個渲染列表的組件，他的職責就是渲染列表，但是我們在這裏也處理了單個Item的邏輯，我們可以將其進行職責分離,List只做列表染，而Gist也只渲染自身

const Gist = ({description}) => (
  <li>
    {description}
  </li>
)

const List = ({gists}) => {
  if (gists.pending) {
    return <div>loading...</div>
  } else if (gists.rejected) {
    return <div>{gists.reason}</div>
  } else if (gists.fulfilled) {
    return (
      gists.fulfilled && <ul>
        {gists.value.map(gist => <Gist key={gist.id} {...gist} />)}
      </ul>
    )
  }
}

使用react-refetch來給Gist添加功能

react-refetch的connect方法接收一個函數作爲參數，這個函數返回一個對象，如果結果對象的值是一個字符串，那麼獲取prop後，會對這個字符串發起請求，但是如果值是一個函數，那麼不會立即執行，而是會傳遞給組件，以便後續使用

值爲字符串
const connectWithStar = refetchConnect(() => ({gists: `https://api.github.com/users/gaearon/gists`}))

值爲函數
const connectWithStar = refetchConnect(({id}) => ({
  star: () => ({
    starResponse: {
      url: `https://api.github.com/gists/${id}/star?${token}`,
      method: 'PUT'
    }
  })
}))

const Gist = ({description, star}) => (
  <li>
    {description}
    <button onClick={star}>+1</button>
  </li>
)

加工Gist組件，star函數會被傳遞給Gist的prop，然後就可以在Gist裏面使用了
connectWithStar(Gist)