Question

I need to fetch the data from two different API endpoints, and after both data is fetched I should do something with those data (ie. compare the data from two sources).

I know how to fetch the data from one API, and then call the callback function to do something with the data. I am doing this as follows.

function getJSON(options, cb) {
   http.request(options, function(res){
       var body = "";

       res.on("data", function(chunk){
          body += chunk;
      });

       res.on("end", function(){
          var result = JSON.parse(body);
          cb(null, result);
      });

       res.on("error", cb);
   })
   .on("error", cb)
   .end();
}

var options = {
    host: "api.mydata1.org",
    port: 8080,
    path: "/data/users/3",
    method: "GET"
}

getJSON(options, function(err, result) {
    if (err) {
        return console.log("Error getting response: ", err);
    }

    // do something with the data

});

Now, what I would want to have something like:

var options2 = {
        host: "api.mydata2.org",
        port: 8080,
        path: "/otherdata/users/3",
        method: "GET"
    }

Those would be the options to connect to the other API, and have a single callback function that would get called whenever the data from both APIs is loaded. How can I do that?

Answer 1

我建议使用request-promise模块返回表示异步操作的promises，然后您可以使用Promise.all()跟踪它们何时完成，然后访问它们的结果：

const rp = require('request-promise');

function getJSON(options) {
    return rp(options).then(body => {
        return JSON.parse(body);
    });
}

let options1 = {
    host: "api.mydata1.org",
    port: 8080,
    path: "/data/users/3",
    method: "GET"
};

let options2 = {
        host: "api.mydata2.org",
        port: 8080,
        path: "/otherdata/users/3",
        method: "GET"
};

Promise.all([getJSON(options1), getJSON(options2)]).then(results => {
    // process results here
    console.log(results[0]);      // from options1 request
    console.log(results[1]);      // from options2 request
}).catch(err => {
    // process error here
    console.log(err);
});

您可以阅读Promise.all() on MDN。网上有很多关于承诺的文章和教程。这是one。它们是ES6 Javascript的标准配置，并且已经在ES5中通过库提供多年。它们是Javascript语言中用于管理或协调异步操作的选定方案。如果您在Javascript中进行任何异步编程（几乎所有node.js编程都可以），那么您应该学习承诺。

Synchronized multiple API calls

1 个答案: