努力得到callback工作express.js
在呈现页面之前试图确定请求已经完成
应用程序概述 – 提交代码，发出请求，填充结果页面
//Index.js
var response = require('./requestMapping') // home search page exports.index = function(req, res){ res.render('index', { stationDisplay: response.station_id, test: 'rob' }); }; **//post from form to call METAR service exports.post =('/', function(req, res, next) { response.getMETAR(req.body.query,function(){ res.render('results', { stationDisplay: response.station_id, test: 'rob' }); }); })** //Index.ejs
<!DOCTYPE html> <html> <head> <title><%= stationDisplay %></title> <link rel='stylesheet' href='/stylesheets/style.css' /> </head> <body> <h1>Enter ICAO code to get the latest METAR</h1> <form method="post" action="/"> <input type="text" name="query"> <input type="submit"> </form> </body> </html>
调用webservice的模块 – requestMapping.js
/** * @author robertbrock */ //Webservice XML function getMETAR(ICAO){ var request = require('request'); request('http://weather.aero/dataserver_current/httpparam?datasource=metars&requestType=retrieve&format=xml&mostRecentForEachStation=constraint&hoursBeforeNow=24&stationString='+ICAO, function(error, response, body){ if (!error && response.statusCode == 200) { var XmlDocument = require('xmldoc').XmlDocument; var results = new XmlDocument(body); console.log(body) console.log(ICAO) exports.station_id = results.valueWithPath("data.METAR.station_id"); //etc. } }) } exports.getMETAR =getMETAR;
我看不到你的getMETAR函数实际上需要一个callback函数？ 我期望它是：
function getMETAR(ICAO, callback) { // Do your work var station_id = results.valueWithPath("data.METAR.station_id"); callback(null, station_id); // It's common to use the first arg of the callback if an error has occurred }
然后调用这个函数的代码可以像这样使用它：
app.post('/', function(req, res) { response.getMETAR(req.body.query, function(err, station_id) { res.render('results', {stationDisplay: station_id, test: 'rob'}; }); });
花了一些时间习惯asynchronous编程，以及callback是如何工作的，但是一旦你完成了几次，你就可以掌握它了。
没有看到你的代码的其余部分很难猜测，但你的代码应该看起来更像是：
app.post('/', function(req, res, next) { response.getMETAR(req.body.query,function(){ res.render('results', { stationDisplay: response.station_id, test: 'rob' }); }); });