无法使用nodejs进行GET？(Cannot GET with nodejs?)

 我有一些简单的nodejs应用程序与一些用户。 我想使用URL localhost / users /（username）加载特定的用户配置文件，但是当我尝试加载URL时出现此错误： 
 
Cannot GET /users/test
 
 这是我的用户页面的user.js路由文件： 
 
var express = require('express');
var router = express.Router();
var User = require('../models/user');

// GET user by username
router.get('/users/:username', function(req, res) {
  var username = req.params.username;
  res.send(req.params);
  res.render('user');
});

module.exports = router;
 
 我在我的视图文件夹中有一个user.handlebars文件，所以它应该加载文件。 我在路线文件中缺少什么？ 任何帮助将不胜感激。 谢谢！！ 
 
 编辑：app.js： 
 
console.log('Starting app.js');

const fs = require('fs');
const _ = require('lodash');
const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;
const mongo = require('mongodb');
const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost/tipcup');
var db = mongoose.connection;

const routes = require('./routes/index');
const users = require('./routes/users');
const user = require('./routes/user');

// Init App
var app = express();

// View Engine
app.set('views', path.join(__dirname, 'views'));
app.engine('handlebars', exphbs({defaultLayout: 'layout'}));
app.set('view engine', 'handlebars');

// BodyParser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false}));
app.use(cookieParser());

// Set Static Folder
app.use(express.static(path.join(__dirname, 'public')));

// Express Session
app.use(session({
  secret: 'secret',
  saveUninitialized: true,
  resave: true
}));

// Passport Init
app.use(passport.initialize());
app.use(passport.session());

// Express Validator
app.use(expressValidator ({
  errorFormatter: function(param, msg, value) {
    var namespace = param.split('.')
    , root = namespace.shift()
    , formParam = root;

    while(namespace.length){
      formParam += '[' + namespace.shift() + ']';
    }
    return {
      param: formParam,
      msg: msg,
      value: value
    };
  }
}));

// Connect Flash
app.use(flash());

// Global Vars
app.use(function (req, res, next){
  res.locals.success_msg = req.flash('success_msg');
  res.locals.error_msg = req.flash('error_msg');
  res.locals.error = req.flash('error');
  res.locals.user = req.user || null;
  next();
});

app.use('/', routes);
app.use('/users', users);
app.use('/users/:username', user);

// Set Port
app.set('port', (process.env.PORT || 3000));

app.listen(app.get('port'), function(){
  console.log('Server started on port '+app.get('port'));
});

I have a simple nodejs app with some users. I want to load a specific user profile using a URL localhost/users/(username) but I'm getting this error when I try to load the URL:
 
Cannot GET /users/test
 
Here's my user.js routes file for the user page:
 
var express = require('express');
var router = express.Router();
var User = require('../models/user');

// GET user by username
router.get('/users/:username', function(req, res) {
  var username = req.params.username;
  res.send(req.params);
  res.render('user');
});

module.exports = router;
 
I have a user.handlebars file in my views folder so it should load the file. What am I missing in my routes file? Any help would be greatly appreciated. Thanks!!
 
EDIT: app.js:
 
console.log('Starting app.js');

const fs = require('fs');
const _ = require('lodash');
const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;
const mongo = require('mongodb');
const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost/tipcup');
var db = mongoose.connection;

const routes = require('./routes/index');
const users = require('./routes/users');
const user = require('./routes/user');

// Init App
var app = express();

// View Engine
app.set('views', path.join(__dirname, 'views'));
app.engine('handlebars', exphbs({defaultLayout: 'layout'}));
app.set('view engine', 'handlebars');

// BodyParser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false}));
app.use(cookieParser());

// Set Static Folder
app.use(express.static(path.join(__dirname, 'public')));

// Express Session
app.use(session({
  secret: 'secret',
  saveUninitialized: true,
  resave: true
}));

// Passport Init
app.use(passport.initialize());
app.use(passport.session());

// Express Validator
app.use(expressValidator ({
  errorFormatter: function(param, msg, value) {
    var namespace = param.split('.')
    , root = namespace.shift()
    , formParam = root;

    while(namespace.length){
      formParam += '[' + namespace.shift() + ']';
    }
    return {
      param: formParam,
      msg: msg,
      value: value
    };
  }
}));

// Connect Flash
app.use(flash());

// Global Vars
app.use(function (req, res, next){
  res.locals.success_msg = req.flash('success_msg');
  res.locals.error_msg = req.flash('error_msg');
  res.locals.error = req.flash('error');
  res.locals.user = req.user || null;
  next();
});

app.use('/', routes);
app.use('/users', users);
app.use('/users/:username', user);

// Set Port
app.set('port', (process.env.PORT || 3000));

app.listen(app.get('port'), function(){
  console.log('Server started on port '+app.get('port'));
});

原文：https://stackoverflow.com/questions/48598516