express 4.0 connect-mongo 运行时报错

app.use(expressSession({
  secret: 'SECRET',
  cookie: {maxAge: 60*60*1000},
  store: new mongoStore({
      db: mongoose.connection.db,
      collection: 'sessions'
    })
  }));

替换成

app.use(expressSession({
    secret: 'SECRET',
    name: 'weizai',
    store:new mongoStore({
    	url:'mongodb://localhost/myapp'
    }),
    // store: new mongoStore({
    //   db: mongoose.connection.db,
    //   collection: 'sessions'
    // }),
    proxy: true,
    resave: true,
    saveUninitialized: true
}));

https://github.com/nswbmw/N-blog

（connect-mongo版本的问题）