ExpressJS中存在数据库中的session如何自动清理？

Question

能不能自动清理呢？大致的代码如下：

var mongoStore = require("connect-mongo")(express);
...
app.use(express.session({
    secret  : "foo",
    store   : new mongoStore({
        db  : "bar"
    })
}));

平时在用的时候直接就是：

exports.blah = function(req, resp) {
    req.session.user = blahblah;
};

随着时间的推移，发现我的mongodb的相应collection中的session数据越来越多，貌似是因为没有清除引起的？

所以想问一下，怎么让数据库中的session数据自己回收呢？THX。

Answer 1

根据 connect-mongo 的文档：

By connect/express's default, session cookies are set to expire when the user closes their browser (maxAge: null). In accordance with standard industry practices, connect-mongo will set these sessions to expire two weeks from their last 'set'. You can override this behavior by manually setting the maxAge for your cookies -- just keep in mind that any value less than 60 seconds is pointless, as mongod will only delete expired documents in a TTL collection every minute.

即是说，默认情况下 Express 的 session cookie 关闭浏览器后就失效，而 mongo 则会在两周后删除相关记录。

如果想 session 和数据库中的记录同时失效呢，可以这么做：

app.use(express.session({
  secret: ......, 
  cookie: { maxAge: 1 * 60 * 60 * 1000 }, // 1 hour
  store: ......
}))