Pre-routing with querystrings with Express in Node JS

Question

I'm trying to use express to parse the querystring in case certain parameters are set and execute a little piece of code, before the actual routing is happening. The use-case is to grab a certain value, that could be set, independant of what link is being used. I use express' functionality to pass the stuff to the next possible rule using next().

So far, I tried - at the very top of all the app.get/post-rule-block:

app.get('[?&]something=([^&#]*)', function(req, res, next) {
  var somethingID = req.params.something;
  // Below line is just there to illustrate that it's working. Actual code will do something real, of course.
  console.log("Something: "+somethingID);
  next();
})

app.get('/', site.index);

and also:

app.param('something', function(req, res, next) {
  var somethingID = req.params.something;
  console.log("Something: "+somethingID);
  next();
})

app.get('/', site.index);

Example of what should be triggered:

URL: www.example.com/?something=10239
URL: www.example.com/superpage/?something=10239
URL: www.example.com/minisite/?anything=10&something=10239

Unfortunately, none of my solutions actually worked, and all that happens is, that the next matching rule is triggered, but the little function above is never executed. Anybody have an idea, of how this can be done?

EDIT: I do understand, that the param-example wasn't working, as I'm not using said parameter within any other routing-rule afterwards, and it would only be triggered then.

I also do understand, that logic implies, that Express ignores the querystring and it is normally parsed within a function after the routing already happened. But as mentioned, I need this to be "route-agnostic" and work with any of the URL's that are processed within this application.

Answer 1

express does not allow you to route based on query strings. You could add some middleware which performs some operation if the relevant parameter is present;

app.use(function (req, res, next) {
    if (req.query.something) {
        // Do something; call next() when done.
    } else {
        next();
    }
});

app.get('/someroute', function (req, res, next) {
    // Assume your query params have been processed
});

Answer 2

Ok, there is quite a logical flaw in here. Routing only uses the URL, and ignores the querystring.

The (or better "A") solution is actually this:

app.get('*', function(req, res, next) {
  if (req.query.something) {
    console.log("Something: "+req.query.something);
  };
  next();
})

Explanation: As Express is ignoring the querystring for the routing, the only regular expression matching all URL's is "*". Once that is triggered, I can check if said querystring is existing, do my logic and continue the routing matching the next rule by using "next()".

And yes: facepalm