Question

我对外部帖子请求进行了测试。所以我这样开始我的应用程序：

var http = require('http');
var extreq = require('./app/external-request');

http.createServer(function (request, response) {

     response.writeHead(200, {'Content-Type': 'text/plain'});

     var aaa = extreq.login();

     response.end(JSON.stringify(aaa));

}).listen(1337, "127.0.0.1");

在“external-request.js”中，我有：

function login() {
     request.post(url, { form: {
               userid: 'myuserid',
               password: '*****'
          }
     }, function (error, response, body) {
          if (!error && response.statusCode == 200) {
               var json = JSON.parse(body);
               console.log(json); // Work
               return json; // Not work
          }
     });
}

module.exports.login = login;

我的问题是，如何在这里获得“return json”“var aaa = extreq.login（）;”？

Answer 1

这里的问题是request.post()。这是一个异步方法，因此您的登录功能完成并在request.post()调用完成之前返回。以下将显示实际情况：

function login() {
    // obviously, you'll need to make sure you include whatever resources
    // you need from 'external-request.js' before this
    request.post(url, { form: { userid: 'myuserid', password: '*****' } },
        function (error, response, body) {
            if (!error && response.statusCode == 200) {
                var json = JSON.parse(body);
                // this will log *after* the note in your main response body
                console.log('this is the second thing your code will log to the console');
                console.log(json); // Work
                // this return doesn't actually go anywhere, it's just lost
                return json; // Not work
            }
    });
    return { whoops: 'this is what we really return' };
}

var http = require('http');

http.createServer(function (request, response) {

    response.writeHead(200, {'Content-Type': 'text/plain'});

    var aaa = extreq.login();

    console.log('this is the first thing your code will log to the console');

    response.end(JSON.stringify(aaa));

}).listen(1337, "127.0.0.1");

...运行它，你会看到你的代码没有像你期望的那样执行。

当人们提到使用回调时，他们所说的是你需要在request完成在回调函数中发布外部请求时打包你想要发生的功能，然后它就可以了当它准备就绪时完成它的工作。如下所示：

var http = require('http');
var extreq = require('./app/external-request.js');

http.createServer(function (request, response) {

    response.writeHead(200, {'Content-Type': 'text/plain'});

    extreq.login(function(aaa) {
        response.end(JSON.stringify(aaa));
    });
    console.log('this is the first thing your code will log to the console');
}).listen(1337, "127.0.0.1");

...然后，您的登录功能：

function login(callback) {
    request.post(url, { form: { userid: 'myuserid', password: '*****' } },
        function (error, response, body) {
            if (!error && response.statusCode == 200) {
                var json = JSON.parse(body);
                // this will log *after* the note in your main response body
                console.log('this is the second thing your code will log to the console');
                console.log(json); // Work
                // bonus points: pass in body directly, and skip stringify
                callback(json);
            }
    });
    return { whoops: 'this is what we really return' };
}

request.post如何让身体回归？

1 个答案: