ExpressJS: How to know when a request has finished?

Question

In an ExpressJS set up on top of NodeJS, I have a bit of code like this:

app.get('/keys/readresults/:keyname', basic_auth, function(req,res){
    res.writeHead(200, {'content-type': 'text/json'});
    setInterval(
        go_to_database_and_get('stuff', function (database_replies) {
        res.write(database_replies)
        })
    ,5000);
});

The code is wrote like that for simplicity (if anyone wants the real code I'm happy to post it in some pastebin).

What happens when I curl -u username:password http://localhost:4000/keys/readresults/key is exactly what I wanted to happen: I get a 200 status header, it checks the database for any results I want and writes the response back to me, then waits 5 seconds and searches for new results in the database and writes the response again, and so on every interval of 5 seconds.

The problem is that when I exit curl, the loop keeps on going forever. How do I tell express or nodejs that it's supposed to end that loop (with clearInterval I guess) as soon as the request has ended?

Answer 1

req.on('close', ...) no longer works in Express 4. Use the on-finished middleware.

Answer 2

req.on("close")

So simply

app.get('/keys/readresults/:keyname', basic_auth, function(req,res){
    res.writeHead(200, {'content-type': 'text/json'});
    var no = setInterval(
        go_to_database_and_get('stuff', function (database_replies) {
        res.write(database_replies)
    });
    ,5000);
    req.on("close", function() {
        clearInterval(no);
    });
});

Answer 3

With express 4.X it is req.on("end", () => {}) , it is better to add this as a express middleware.

Yeah but on-finished npm package works too.