React - 異步api調用，Promise.all等待調用完成

Question

一個api調用我返回這個（一般的時間表列表）：

const schedules = {
  data: [
    {
      id: "2147483610",
      selfUri: "/schedules/2147483610",
      type: "Schedule",
      status: "Pending"
    },
    {
      id: "2147650434",
      selfUri: "/schedules/2147650434",
      type: "Schedule",
      status: "Pending"
    }
  ],

在單獨請求每個schedule.data.selfUri之前，這些計划不會在服務器上啟動。 那么有沒有辦法拉出每個selfUri's並在不同的api調用中請求每個selfUri's ？

使用Promise.all這是正確的方法嗎？

Promise.all(this.state.scheduleUri.map((uri) => { return axios.get(uri, ...); }));

通常使用axios我會做這樣的事情：

axios({
  method: "get",
  url: `/get/data`
})
.then(response => {
    console.log(response);
    this.setState(
      {
        someState: response.data
      });
  })
  .catch(error => console.log(error.response));
};

Answer 1

是的， 單個Promise和Promise.all之間的組合將起到作用 。

這是我如何處理這個問題：

// Step 1: get your schedules list.
axios.get('/get/schedules')
  .then(response => {
    const schedules = response.data;

    // Step 2: get each of your schedules selfUri data.
    // This line gets called after the schedule list is received
    // However, Promise.all executes all calls asynchroniously, at once.
    return Promise.all(schedules.map(schedule => axios.get(schedule.selfUri)));
  }
  .then(responseArray => {
    // Step 3: Finally, here you have available
    // the responses from the Promise.all call in Step 2.
    // Or in other words, responseArray holds the response
    // for each of the selfUri calls.

    this.setState({
      // do whatever you want with the data ;-)
    })
  })
  .catch(error => console.log(error.response));

聽起來像一個合理的計划。

Answer 2

您無需等待所有請求完成，但一旦返回就會逐個處理：

 axios.get('/get/schedules') .then(response => { const schedules = response.data; schedules.forEach(schedule => axios.get(schedule.selfUri) .then(responseArray => { this.setState({ .... }) }); ) })