1: C:\Node_app\microblog\node_modules\connect-mongo\lib\connect-mongo.js:126
2: throw new Error('Error connecting to database');
3: ^
4: Error: Error connecting to database
5: at module.exports.MongoStore.__proto__ (C:\Node_app\microblog\node_module
6: at Db.open (C:\Node_app\microblog\node_modules\connect-mongo\node_modules
7: at Server.connect.connectionPool.on.server._serverState (C:\Node_app\micr
8: ion\server.js:408:7)
9: at EventEmitter.emit (events.js:115:20)
10: at connection.on.connectionStatus (C:\Node_app\microblog\node_modules\con
11: :93:15)
12: at EventEmitter.emit (events.js:91:17)
13: at Socket.errorHandler (C:\Node_app\microblog\node_modules\connect-mongo\
14: at Socket.EventEmitter.emit (events.js:88:17)
15: at Socket._destroy.self.errorEmitted (net.js:329:14)
16: at process.startup.processNextTick.process._tickCallback (node.js:244:9)
与此类似node throwing error on mongodb，一直报Db.open那里出错，查源代码，发现应该是有err参数传入，因为之前从来没接触过mongodb--在某些文章中看到稍微有些了解，觉得是不是没有安装mongodb的问题呢？试了一下，果然如此。
windows下安装mongodb：
1、下载MongoDB，下载页面>>
2、解压安装，因为我电脑的C盘非系统盘，默认是我工作目录，所以我先解压到这个盘里。c:\mongodb (解压出来有一个bin目录，里面很多exe文件)，然后再建立一个目录和文件
c:\mongodb\logs\mongodb.log
3、建立MongoDB的数据存放目录，假设为c:\mongodb_data\db
4、启动Mongo Db服务，如果控制台上看到类似的信息，则说明启动成功
默认MongoDB监听的端口是27017，mysql的是3306
5、测试连接
新开一个cmd窗口，进入mongodb的bin目录，输入mongo.exe，出现如下信息说明测试通过
继续测试
1: >use test
2: sitched to db test
3: >db.foo.save({hello:1, word:2})
4: >db.foo.find()
5: "_id" : ObjectId("500a5fde4ad5d4c1884a5c3f"), "hello" : 1, "word" : 2 }
然后输入exit，退出窗口，然后再输入exit关闭该dos
6、注册MongoDB为系统服务。
1: C:\mongodb\bin>mongod.exe --dbpath=c:\mongodb_data\db --logpath=c:\mongodb\logs\mongodb.log --install
如果需要卸载该服务，使用“sc delete MongoDB”即可
7、启动mongodb服务
net start MongoDB
打开任务管理器，可以看到进程已经启动
如果需要停止服务： net stop MongoDb
再次启动app，发现可以正常启动了
到这里express中使用mongodb来保存session就可以正常工作了，app.js的代码如下：
1:
2: /**
3: * Module dependencies.
4: */
5:
6: var express = require('express');
7: var http = require('http');
8: var routes = require('./routes');
9:
10: var settings = require('./settings');
11:
12: var MongoStore = require('connect-mongo')(express);
13: //var connect = require('connect');
14: //var MongoStore = require('connect-mongo')(connect);
15:
16:
17: var sessionStore = new MongoStore({
18: db : settings.db
19: }, function() {
20: console.log('connect mongodb success...');
21: });
22:
23:
24:
25: var app = express();
26:
27: app.configure(function(){
28: app.set('port', process.env.PORT || 3000);
29: app.set('views', __dirname + '/views');
30: app.set('view engine', 'jade');
31: app.use(express.favicon());
32: app.use(express.logger('dev'));
33: app.use(express.bodyParser());
34: app.use(express.methodOverride());
35:
36: app.use(express.cookieParser());
37:
38: app.use(express.session({
39: secret : settings.cookie_secret,
40: store : sessionStore,
41: cookie : {
42: maxAge : new Date(Date.now() + 1000 * 60 * 60)
43: }
44: }));
45:
46: app.use(app.router);
47: app.use(express.static(__dirname + '/public'));
48: });
49:
50: app.configure('development', function(){
51: app.use(express.errorHandler());
52: });
53:
54: app.get('/', routes.index);
55:
56:
57: http.createServer(app).listen(app.get('port'), function(){
58: console.log("Express server listening on port " + app.get('port'));
59: });
