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)與此類似node throwing error on mongodb，一直報Db.open那裏出錯，查源代碼，發現應該是有err參數傳入，因爲之前從來沒接觸過mongodb--在某些文章中看到稍微有些瞭解，覺得是不是沒有安裝mongodb的問題呢？試了一下，果然如此。
windows下安裝mongodb：
1、下載MongoDB，下載頁面>>
2、解壓安裝，因爲我電腦的C盤非系統盤，默認是我工作目錄，所以我先解壓到這個盤裏。c:\mongodb (解壓出來有一個bin目錄，裏面很多exe文件)，然後再建立一個目錄和文件
c:\mongodb\logs\mongodb.log
3、建立MongoDB的數據存放目錄，假設爲c:\mongodb_data\db
4、啓動Mongo Db服務，如果控制檯上看到類似的信息，則說明啓動成功
默認MongoDB監聽的端口是27017，mysql的是3306
5、測試連接
新開一個cmd窗口，進入mongodb的bin目錄，輸入mongo.exe，出現如下信息說明測試通過
繼續測試
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 }
然後輸入exit，退出窗口，然後再輸入exit關閉該dos
6、註冊MongoDB爲系統服務。
1: C:\mongodb\bin>mongod.exe --dbpath=c:\mongodb_data\db --logpath=c:\mongodb\logs\mongodb.log --install
如果需要卸載該服務，使用“sc delete MongoDB”即可
7、啓動mongodb服務
net start MongoDB
打開任務管理器，可以看到進程已經啓動
如果需要停止服務： net stop MongoDb
再次啓動app，發現可以正常啓動了
到這裏express中使用mongodb來保存session就可以正常工作了，app.js的代碼如下：
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: });