Cannot get POST data

[dieka2501]

hello Mr Han and Mr Jollen, how are you?

i want to ask something, how to get the post data? I try post data but it always show error

TypeError: Cannot read property 'user' of undefined at Object.handle (/home/dikdik/nodeapp/router/main.js:11:26) at next_layer (/home/dikdik/nodeapp/node_modules/express/lib/router/route.js:103:13) at Route.dispatch (/home/dikdik/nodeapp/node_modules/express/lib/router/route.js:107:5) at c (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:195:24) at Function.proto.process_params (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:251:12) at next (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:189:19) at next (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:166:38) at Layer.expressInit as handle at trim_prefix (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:226:17) at c (/home/dikdik/nodeapp/node_modules/express/lib/router/index.js:198:9)

i try googling it, but still didn't get any result.
this is my source code.

//server.js
var express=require('express');
var bodyParser = require('body-parser');
var http = require('http');
var app=express();

require('./router/main')(app);
app.set('views',__dirname+'/views');
app.set('view engine','ejs');
app.engine('html',require('ejs').renderFile);
app.use(bodyParser.text());
app.use(bodyParser.urlencoded({extended:true}));
var server=app.listen(3000,function(){
console.log("Started listen port 3000");
});

//main.js
module.exports=function(app){

app.get('/',function(req,res){
    var body = '';
    var url  = "http://localhost:3000/";
    res.render('index.html',{title:'Apa atuh',content:'Ini content',url:url});
});
app.post('/about',function(req,res){
    var username = req.body.user;
    var password = req.body.pass;
    res.render('about.html',{user:username,pass:password});
});

}

i start to learn again nodejs, but i already forget about it, can you help me?