多谢！

@nswbmw 跟到注册功能卡住了，貌似 session 有问题？

routes/index.js 有关 reg 的部份：

   app.get('/reg', function(req,res){
        res.render('reg',{
            title: '注册',
            user: req.session.user,
            success: req.flash('success').toString(),
            error: req.flash('error').toString()
        });
    });
    app.post('/reg', function(req,res){
        if(req.body['password-repeat'] != req.body['password']){
            req.flash('error','两次输入的口令不一致');
            return res.redirect('/reg');
        }
        var md5 = crypto.createHash('md5');
        var password = md5.update(req.body.password).digest('base64');
        var newUser = new User({
            name: req.body.username,
            password: password,
        });
        User.get(newUser.name, function(err, user){
            if(user){
                err = '用户已存在';
            }
            if(err){
                req.flash('error', err);
                return res.redirect('/reg');
            }
            newUser.save(function(err){
                if(err){
                    req.flash('error',err);
                    return res.redirect('/reg');
                }
                req.session.user = newUser;
                req.flash('success','注册成功');
                res.redirect('/');
            });
        });
    });

models/user.js:

var mongodb = require('./db');

function User(user){
    this.name = user.name;
    this.password = user.password;
};

module.exports = User;

User.prototype.save = function save(callback) {
  var user = {
      name: this.name,
      password: this.password,
  };


  mongodb.open(function(err, db){
      if(err){
          return callback(err);
      }

      db.collection('users', function(err, collection){
          if(err){
              mongodb.close();
              return callback(err);
          }

          collection.ensureIndex('name',{
              unique:true
          });

          collection.insert(user,{safe: true}, function(err, user){
              mongodb.close();
              callback(err, user);
          });
      });
    });
};

User.get = function get(username, callback){
mongodb.open(function(err, db){
  if(err){
    return callback(err);
  }

  db.collection('users', function(err, collection){
    if(err){
      mongodb.close();
      return callback(err);
    }

    collection.findOne({
      name: username
    },function(err, doc){
        mongodb.close();
        if(doc){
          var user = new User(doc);
          callback(err, user);
        } else {
          callback(err, null);
        }
    });
  });
});
};

app.js

/**
 * Module dependencies.
 */

var express = require('express')
  , routes = require('./routes')
  , user = require('./routes/user')
  , http = require('http')
  , path = require('path')
  , MongoStore = require('connect-mongo')(express)
  , settings = require('./settings')
  , flash = require('connect-flash');

var app = express();

// all environments
app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');
app.use(flash());
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));
app.use(express.cookieParser());
app.use(express.Session({
      secret: settings.cookieSecret,
      store:
        new MongoStore({
                    db: settings.db
        })
}));

// development only
if ('development' == app.get('env')) {
  app.use(express.errorHandler());
}

app.use(function(req,res,next){
  var err = req.flash('error');
  var success = req.flash('success');
  res.locals.user = req.session.user;
  res.locals.error = err.length ? err : null;
  res.locals.success = success.length ? success : null;
  next();
});

http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

routes(app);

错误信息：

500 TypeError: Cannot read property 'user' of undefined
at /Users/Mac/nodeprojs/blog/routes/index.js:12:30
at callbacks (/Users/Mac/nodeprojs/blog/node_modules/express/lib/router/index.js:161:37)
at param (/Users/Mac/nodeprojs/blog/node_modules/express/lib/router/index.js:135:11)
at pass (/Users/Mac/nodeprojs/blog/node_modules/express/lib/router/index.js:142:5)
at Router._dispatch (/Users/Mac/nodeprojs/blog/node_modules/express/lib/router/index.js:170:5)
at Object.router (/Users/Mac/nodeprojs/blog/node_modules/express/lib/router/index.js:33:10)
at next (/Users/Mac/nodeprojs/blog/node_modules/express/node_modules/connect/lib/proto.js:190:15)
at Object.methodOverride [as handle] (/Users/Mac/nodeprojs/blog/node_modules/express/node_modules/connect/lib/middleware/methodOverride.js:37:5)
at next (/Users/Mac/nodeprojs/blog/node_modules/express/node_modules/connect/lib/proto.js:190:15)
at multipart (/Users/Mac/nodeprojs/blog/node_modules/express/node_modules/connect/lib/middleware/multipart.js:64:37)

环境：node v0.10.5, express: 3.2.4