How to use Morgan logger?

I cannot log with Morgan. It doesn't log info to console. The documentation doesn't tell how to use it.

I want to see what a variable is. This is a code from response.js file of expressjs framework:

var logger = require("morgan");

res.render = function(view, options, fn){
  options = options || {};
  var self = this;
  var req = this.req;
  var app = req.app;

  // support callback function as second arg
  if ('function' == typeof options) {
    fn = options, options = {};
  }

  // merge res.locals
  options._locals = self.locals;

  // default callback to respond
  fn = fn || function(err, str){
    if (err) return req.next(err);
    self.send(str);
  };

  // Here I want to see what fn is
  // But it doesn't show me anything in console
  // How to use it?
  logger(fn);

  // render
  app.render(view, options, fn);
};

How to use Morgan?

Seems you too are confused with the same thing as I was, the reason I stumbled upon this question. I think we associate logging with manual logging as we would do in Java with log4j (if you know java) where we instantiate a Logger and say log 'this'.

Then I dug in morgan code, turns out it is not that type of a logger, it is for automated logging of requests, responses and related data. When added as a middleware to an express/connect app, by default it should log statements to stdout showing details of: remote ip, request method, http version, response status, user agent etc. It allows you to modify the log using tokens or add color to them by defining 'dev' or even logging out to an output stream, like a file.

For the purpose we thought we can use it, as in this case, we still have to use:

console.log(..);

Or if you want to make the output pretty for objects:

var util = require("util");
console.log(util.inspect(..));

I think I have a way where you may not get exactly get what you want, but you can integrate Morgan's logging with log4js -- in other words, all your logging activity can go to the same place. I hope this digest from an Express server is more or less self-explanatory:

var express = require("express");
var log4js = require("log4js");
var morgan = require("morgan");
...
var theAppLog = log4js.getLogger();
var theHTTPLog = morgan({
  "format": "default",
  "stream": {
    write: function(str) { theAppLog.debug(str); }
  }
});
....
var theServer = express();
theServer.use(theHTTPLog);

Now you can write whatever you want to theAppLog and Morgan will write what it wants to the same place, using the same appenders etc etc. Of course, you can call info() or whatever you like in the stream wrapper instead of debug() -- that just reflects the logging level you want to give to Morgan's req/res logging.

Morgan should not be used to log in the way you're describing. Morgan was built to do logging in the way that servers like Apache and Nginx log to the error_log or access_log. For reference, this is how you use morgan:

var express     = require('express'),
    app         = express(),
    morgan      = require('morgan'); // Require morgan before use

// You can set morgan to log differently depending on your environment
if (app.get('env') == 'production') {
  app.use(morgan('common', { skip: function(req, res) { return res.statusCode < 400 }, stream: __dirname + '/../morgan.log' }));
} else {
  app.use(morgan('dev'));
}

Note the production line where you see morgan called with an options hash {skip: ..., stream: __dirname + '/../morgan.log'}

The stream property of that object determines where the logger outputs. By default it's STDOUT (your console, just like you want) but it'll only log request data. It isn't going to do what console.log() does.

If you want to inspect things on the fly use the built in util library:

var util = require('util');
console.log(util.inspect(anyObject)); // Will give you more details than console.log

So the answer to your question is that you're asking the wrong question. But if you still want to use Morgan for logging requests, there you go.

How to use Morgan logger?

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