Is it possible to get the current request that is being served by node.js?

Question

I am using express.js. I have a need to be able to log certain request data whenever someone tries to log a message. For this I would like to create a helper method like so

function log_message(level, message){
  winston.log(level, req.path + "" + message);
}

I would then use the method like so.

exports.index = function(req, res){
  log_message("info", "I'm here");
}

Note that I am not passing the req object to the log_message function. I want that to be transparently done so that the log_message API user does not need to be aware of the common data that is being logged.

Is there a way to achieve this with express.js/node.js. Is the request object available from a global variable of some sort?

Answer 1

Similar to the domains answer, it's now a lot easier to do this using continuation-local-storage: https://datahero.com/blog/2014/05/22/node-js-preserving-data-across-async-callbacks/

At DataHero we save a transaction id, user id, and session id with all log messages. You don't need to pass the request object all the way down, so it helps keep your models / business layer clean, too.

Answer 2

create a midleware:

app.use(function(req, res, next) {
       var tid = uuid.v4();
     var cls = require('continuation-local-storage');
       var namespace = cls.createNamespace('com.storage');
      var pre_ip;
          if(get_ip(req))
          { ip_info= get_ip(req).clientIp;
              pre_ip=ip_info
          }
          namespace.bindEmitter(req);
          namespace.bindEmitter(res);
        namespace.run(function() {
               console.log(logobj);
              namespace.set('tid', tid);
              namespace.set('ip',ip_info);
           namespace.set('logobj',logobj);   
              next();
          });
      });

And use it :

var cls = require('continuation-local-storage');
 var namespace = cls.getNamespace('com.storage');
      namespace.get('ip');