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

The following solution is acceptable to me.

In here I have a middleware which adds the log_message method onto the request object. After that I simply call req.log_message to log the message. While this is very similar to passing the req object to every logging call it’s just slightly cleaner.

function logging_middleware(req, res, next){
    req.log_message = function(level, message){
        winston.log(level, req.path + ":" + message);
    }
    next();
}