Question

我想避免回调地狱，所以我建立了承诺，但我有点卡住了。

我需要制作getAllDataSource - ＆gt; createDashboard - ＆GT; `sendDashboard``

所以代码是：

var call = Promise.promisify(Meteor.call, Meteor);

var calls = call(getAllDataSource()).
            then(call.bind(Meteor, createDashboard())).
            then(call.bind(Meteor, sendDashboard()));

calls.then(function(resThree){
    console.log("Got Response!", resThree);
}).catch(function(err){
    console.log("Got Error", err); 
});

但是我对第一个变量call感到有点迷茫。我想我需要改变它但是用什么？然后这将如何知道getAllDataSource何时完成？

var allDataSources;
getAllDataSources = Meteor.bindEnvironment(function(){
    HTTP.call("GET", 'http://localhost:3000/api/datasources', {
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json',
                'Authorization': 'Bearer eyJrIjoic2RRbU9oM2Rkbmc0bHZUSjVlTjBPckRVNlplSW1DYzEiLCJuIjoibG9jYWxob3N0X2FkbWluX2tleSIsImlkIjoxfQ==',
            },
        },
        function(error, result) {
            if (!error) {
              allDataSources = result.data;
            } else {
                console.error(error);
            }
        });
});

var sendme;
createDashboard = Meteor.bindEnvironment(function(){
  for (var i = 0; i < 5; i++) {
    console.log("I have " + i + " apples in " + allDataSources);
    sendme = "hihihih";
  }
});

sendDashboard = Meteor.bindEnvironment(function(){
  for (var i = 0; i < 7; i++) {
    console.log("I have " + i + " cats with " + sendme);
  }
});

创建结果时会自动转到方法2吗？

感谢您的帮助

[编辑]这实际上是在控制台上给我的：

Got Error { [Error: Method 'undefined' not found [404]]
I20170209-10:39:30.990(1)?   error: 404,
I20170209-10:39:30.991(1)?   reason: 'Method \'undefined\' not found',
I20170209-10:39:30.991(1)?   details: undefined,
I20170209-10:39:30.991(1)?   message: 'Method \'undefined\' not found [404]',
I20170209-10:39:30.991(1)?   errorType: 'Meteor.Error' }

[EDIT2] 在跟着@ymz的回答后我得到了这个错误：

Got Error { [Error: Method '[object Object],[object Object],[object Object],[object Object]' not found [404]]
I20170209-11:23:48.154(1)?   error: 404,
I20170209-11:23:48.154(1)?   reason: 'Method \'[object Object],[object Object],[object Object],[object Object]\' not found',
I20170209-11:23:48.154(1)?   details: undefined,
I20170209-11:23:48.154(1)?   message: 'Method \'[object Object],[object Object],[object Object],[object Object]\' not found [404]',
I20170209-11:23:48.154(1)?   errorType: 'Meteor.Error' }

我认为它来自var calls = call(data).then .... // proceed from here，因为getAllDataSource()在此处data放置了一个数组。我需要更多的帮助

Answer 1

所以在尝试并尝试后我已经制作了这段代码：

new Promise(function(resolve) {
  console.log("step1")
    // 1. first async task
    HTTP.call("GET", 'http://localhost:3000/api/datasources', {
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json',
                'Authorization': 'Bearer 123',
            },
        },
        function(error, result) {
            if (!error) {
              allDataSources = result.data;
              console.log("step1.5" + allDataSources)
              resolve(allDataSources);
            } else {
                console.error(error);
            }
        });

}).then(function(allDataSources) {
  console.log("step2")
    // 2. second async task
    return new Promise(function(resolve) {
      console.log("step 2.5" + resolve + allDataSources)
      for (var dataSource = 0; dataSource < allDataSources.length; dataSource++) {
         sendme = "sendme";
      }
      resolve(sendme);
    });

}).then(function(sendme) {
    // 3. now we can render the products after two async tasks are done
    console.log('Rending product ' + sendme);
});

我非常感谢帮助我的@ymz

Answer 2

这个问题很棘手，因为它因两个不同因素而失败

Promise
使用异步代码时的错误方法

完整修复：

首先 - 对Bluebird Promise lib使用require：

var Promise = require('bluebird');

第二 - 使用回调处理您的异步代码

function whenDataArrive(data)
{
    if (!data) return;

    var calls = call(data).then .... // proceed from here
}

getAllDataSources = Meteor.bindEnvironment(function(id){
HTTP.call("GET", 'http://localhost:3000/api/datasources', {
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json',
            'Authorization': 'Bearer 123',
        },
    },
    function(error, result) {
        if (!error) {
          whenDataArrive(result.data);
        } else {
            console.error(error);
            whenDataArrive();
        }
    });

}）;

如何使用Meteor承诺进行3次通话

2 个答案: