Cannot read property 'Store' of undefined nodejs express session

Express在使用mongodb的时候app配置出错!  "Cannot read property 'Store' of undefined"

原因主要是express版本4++问题

//settings.js

module.exports={

   cookieSecret:"xxxx",

   db:"dbname",

   host:"localhost",

}

//app.js

var express = require("express");

var settings = require("./settings");

加载connect-mongo的出错写法：

var MongoStore=require("connect-mongo")(express);

app.use(express.session({
    secret:Settings.cookieSecret,
    key:Settings.db,
    cookie:{maxAge:1000*60*60*24*30},//30 days
    store:new MongoStore({
        db:Settings.db
    })
}));

启动后报错：TypeError: Cannot read property 'Store' of undefined

以上是 express<4的写法

express 4.0之后（包括4.0）写法如下：

var session = require("express-session");

var MongoStore=require("connect-mongo")(session);

app.use(session({

   secret:settings.cookieSecret,

   store:new MongoStore({

      db:settings.db

   })

});

package.json配置如下

{
  "name": "dbTest",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node ./bin/www"
  },
  "dependencies": {
    "express": "~4.2.0",
    "static-favicon": "~1.0.0",
    "morgan": "~1.0.0",
    "cookie-parser": "~1.0.1",
    "body-parser": "~1.0.0",
    "debug": "~0.7.4",
    "ejs": "~0.8.5",
    "mongodb":"*",
    "connect-mongo":"*",
    "express-session":"*"
  }
}