从promise.all()返回数据 [英] Returning data from promise.all()

问题描述

我正在尝试使用 promise.all()

function apiReq1(apiCred){
  const rds = new apiCred.RDS();
  var request = rds.describeDBInstances();
  return request.promise();
}

function getAPIs (apiCred) {
  return Promise.all([apiReq1(apiCred), apiReq2(apiCred), apiReq3(apiCred)]).then(function(data) {
    console.log(data[0])
    console.log(data[1])
    console.log(data[2])
    return data

    // ideal return
    //myMap.set('bar', data[0])
    //.set('foo', data[1])
    //.set('baz', data[2]);
    //return myMap
  });
}

// Function that is calling getAPIs
function getAll() {
  apiCred = getApiCred()
  page = getAPIs(apiCred)
  console.log(page)
}

console.log按预期方式打印出数据，但是我希望能够返回 data 对象，或者理想情况下，返回具有所有三个可迭代对象的新对象，以调用 getAPIs().这是我第一次尝试使用Promise，但我觉得在尝试返回数据时缺少一个关键的异步概念.

The console.log prints out the data as expected however I would like to be able to return the data object or ideally a new object with all three iterables to whatever calls getAPIs(). This is the first time I am trying to use promises and I feel there is a key async concept I am missing here on trying to return the data.

推荐答案

您可以这样做:

function getAPIs (apiCred) {
  return Promise.all([apiReq1(apiCred), apiReq2(apiCred), apiReq3(apiCred)]).then(function(data) {
    return {
        'bar': data[0],
        'foo': data[1],
        'baz': data[2]
    }
  });
}

但是，此函数仍返回promise，因此您无法在调用方中同步访问结果.

However, this function still returns a promise, so you cant access the result in the caller synchronously.

您需要按如下所示修改 getAll 方法

You need to modify your getAll method as follows

function getAll() {
  apiCred = getApiCred()
  return getAPIs(apiCred).then(page => {
    console.log(page);
    //DO YOUR THING
  })
} 

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