MongoDB：在集合：会话上设置TTL索引时出错

Question

最初，此错误消息开始很少出现，但开始出现得更规则，现在运行应用程序时出现4/5次。

我正在使用Mongo处理会话存储，据我所知，TTL索引用于使会话数据过期。

/home/dan/dev/audio-wave/node_modules/connect-mongo/lib/connect-mongo.js:161
            throw new Error('Error setting TTL index on collection : ' + s
                  ^
Error: Error setting TTL index on collection : sessions
at /home/dan/dev/audio-wave/node_modules/connect-mongo/lib/connect-mongo.js:161:23
at /home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/db.js:1404:28
at /home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/db.js:1542:30
at /home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/cursor.js:159:22
at commandHandler (/home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/cursor.js:678:48)
at Db._executeQueryCommand (/home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/db.js:1802:12)
at Cursor.nextObject (/home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/cursor.js:729:13)
at Cursor.toArray (/home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/cursor.js:158:10)
at Cursor.toArray (/home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/scope.js:10:20)
at /home/dan/dev/audio-wave/node_modules/connect-mongo/node_modules/mongodb/lib/mongodb/db.js:1541:65

这是将其绑定在一起的代码

var sessionStore = new MongoStore({ db: 'audio-drop' })
  , cookieParser = express.cookieParser('waytoblue')
  , SessionSockets = require('session.socket.io')
  , sockets = new SessionSockets(io, sessionStore, cookieParser);

app.set('port', process.env.PORT || 3000);
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');
app.use(express.favicon());
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(express.static(path.join(__dirname, 'public')));
app.use(express.logger('dev'));
app.use(cookieParser);
app.use(express.session({
  store: sessionStore
}));

根据db.version()Mongo shell的说法，我正在运行2.4.9，并且正在使用0.4.0版connect-mongo。

似乎有很多人遇到了这个问题，但是似乎大多数人都解决了证书问题，我的本地mongo没有经过身份验证的保护，所以这不是问题。有任何想法吗？

Answer 1

正如我在您的评论中所说，本质上Express在会话存储完全连接之前就已接收连接。解决方案是等待连接发生，然后再允许您的应用程序开始监听。

您可以通过在创建MongoStore时使用回调或传入已经处于活动状态的连接来避免此问题。

var sessionStore = new MongoStore({ url: 'someConnectionUrl', db: 'audio-drop' }, function(e) {

  var cookieParser = express.cookieParser('waytoblue');
  app.use(cookieParser);

  app.use(express.session({
    store: sessionStore
  }));

  app.listen();
});

简单的猫鼬例子

var mongoose = require('mongoose');

mongoose.connect('localhost', function(e) {
  // If error connecting
  if(e) throw e;

  var sessionStore = new MongoStore({ mongoose_connection: mongoose.connection }),
      cookieParser = express.cookieParser('waytoblue');

  app.use(cookieParser);

  app.use(express.session({
    store: sessionStore
  }));

  app.listen();
});