Node.js connect mongo需要澄清，如何在nodejs中使用它与express进行会话

在node.js应用程序中，我试图将会话数据存储在mongoDB数据库中

但是的用法对我来说有点困惑，我希望有人能向我解释正确的用法，以及下面提到的所有其他用法

本教程告诉它这样使用它

var express = require('express');
var app = express();
var MongoStore = require('connect-mongo')(express);

app.use(express.cookieParser());
app.use(express.session({
  store: new MongoStore({
    url: 'mongodb://root:myPassword@mongo.onmodulus.net:27017/3xam9l3'
  }),
  secret: '1234567890QWERTY'
}));

//...

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

app.use(express.session({
    secret: settings.cookie_secret,
    store: new MongoStore({
      db: settings.db
    })
  }));

var SessionStore = require('connect-mongo')(express); 
// not sure exactly what was assigned, but this same variable name was used below..

app.configure(function() {
     ...
     app.use(express.session({
         secret: secretSauce,
         store: SessionStore, // < ..here
     }));
     ...
 });

但是主插件站点是这样使用它的

var express = require('express');
var app = express();
var MongoStore = require('connect-mongo')(express);

app.use(express.cookieParser());
app.use(express.session({
  store: new MongoStore({
    url: 'mongodb://root:myPassword@mongo.onmodulus.net:27017/3xam9l3'
  }),
  secret: '1234567890QWERTY'
}));

//...

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

app.use(express.session({
    secret: settings.cookie_secret,
    store: new MongoStore({
      db: settings.db
    })
  }));

var SessionStore = require('connect-mongo')(express); 
// not sure exactly what was assigned, but this same variable name was used below..

app.configure(function() {
     ...
     app.use(express.session({
         secret: secretSauce,
         store: SessionStore, // < ..here
     }));
     ...
 });

它以不同的方式使用

存储

然而，我过去用过这个，虽然我现在不能让它工作，但我用的有点像这样

var express = require('express');
var app = express();
var MongoStore = require('connect-mongo')(express);

app.use(express.cookieParser());
app.use(express.session({
  store: new MongoStore({
    url: 'mongodb://root:myPassword@mongo.onmodulus.net:27017/3xam9l3'
  }),
  secret: '1234567890QWERTY'
}));

//...

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

app.use(express.session({
    secret: settings.cookie_secret,
    store: new MongoStore({
      db: settings.db
    })
  }));

var SessionStore = require('connect-mongo')(express); 
// not sure exactly what was assigned, but this same variable name was used below..

app.configure(function() {
     ...
     app.use(express.session({
         secret: secretSauce,
         store: SessionStore, // < ..here
     }));
     ...
 });

var SessionStore=require（'connect-mongo'）（express）；
//不确定到底分配了什么，但下面使用了相同的变量名。。
app.configure（函数（）{
...
应用程序使用（express.session）({
秘密：秘制酱汁，
商店：SessionStore，//<…此处
}));
...
});

我以前的方式对我来说似乎更优雅了，但它并没有像现在这样起作用。我无法理解前两个例子中发生了什么，为什么它们如此不同。有人能解释一下我需要从这两个人那里做些什么来达到我的目的吗
 这让它起作用了

var MongoStore = require('connect-mongo')(express);
var SessionStore = new MongoStore({
    db: 'SessionStore'
});

app.use(express.session({
    secret: secretSauce,
    store: SessionStore,
}));