Save before req.session.destroy() ExpressJS

Question

I want to save the session value "image location" into the database before I have destroyed the session in logout route

The solution adopted by me is :

app.get('/logout',function(req,res){

    Person.update({ username: req.session.user_name }, { $set: {lastimage: req.session.userimage[req.session.img_idx]}}, function(error,update)
            {
                if(update){ 
                req.session.destroy(function() {
                     res.end();
                });
                if(error){
                    console.log(error);
                    res.end();
                }

                }       

            });
});

But when I am using this get location route the task is accomplished ie the value in person db is updated but in return there is some weird error shown

TypeError: Cannot read property 'undefined' of undefined
    at options.key (/opt/expressjs/app.js:381:94)
    at callbacks (/opt/expressjs/node_modules/express/lib/router/index.js:164:37)
    at param (/opt/expressjs/node_modules/express/lib/router/index.js:138:11)
    at pass (/opt/expressjs/node_modules/express/lib/router/index.js:145:5)
    at Router._dispatch (/opt/expressjs/node_modules/express/lib/router/index.js:173:5)
    at Object.router (/opt/expressjs/node_modules/express/lib/router/index.js:33:10)
    at next (/opt/expressjs/node_modules/express/node_modules/connect/lib/proto.js:193:15)
    at resume (/opt/expressjs/node_modules/express/node_modules/connect/lib/middleware/static.js:65:7)
    at SendStream.error (/opt/expressjs/node_modules/express/node_modules/connect/lib/middleware/static.js:80:37)
    at SendStream.EventEmitter.emit (events.js:95:17)

Why is it so. I am using ExpressJs sessions and mongodb

PS: The line /opt/expressjs/app.js:381:94 is

Person.update({ username: req.session.user_name }, { $set: {lastimage: req.session.userimage[req.session.img_idx]}}, function(error,update)

Answer 1

Have you tried saving

'req.session.userimage[req.session.img_idx]' in some var before use ?

for example:

var uName = req.session.user_name,
    uImage = req.session.userimage[req.session.img_idx];

Person.update({ username: uName }, { $set: {lastimage: uImage }}, function(error,update) { ...

BTW, you may be calling res.end() twice, which will make things weird.

EDIT:

app.get('/logout', function(req,res) {

    var uName  = req.session.user_name,
        uImage = req.session.userimage[req.session.img_idx];

    Person.update({ username: uName }, { $set: {lastimage: uImage }}, function(error,update) {

        if(error)
            console.log(error);

        // This actually destroys the session
        delete req.session;
        res.end();
    });
});