如何写入Node.js Connect / Express记录器？

Question

I have an Express project and I have it set up to log to a file:

logPath = '/mnt/log/api.log'
logfile = fs.createWriteStream logPath, {flags: 'a'} 

loggingOptions = 
  format: 'default'
  stream: logfile

app.use express.logger(loggingOptions)

This works for logging requests, but I want to add my own messages to the log, but I can't figure out how. console.log isn't redirected, and there doesn't seem to be a "logger" object created that I can write to.

So is my only option to pass around a reference to the file stream and write to that?

Answer 1

I don't know how to do exactly what you are asking but this is what I do and so far it has worked well.

I configure the express logger (which is actually the connect logger by the way if you are looking for documentation) like shown below and all the log output goes to stdout. I can print to the same output with console.log("blah blah").

app.use(express.logger("default"));

On the production server I redirect all the output of node to to the log file.

This works well during development too because I run node in a shell window and can see all the same output. (Actually I use express.logger("dev") during development because the output is much cleaner for dev work.)

Answer 2

You could create your own logging middleware:

app.use (req, res, next) ->
   logFile.write "anything you want"
   next()

Answer 3

Define error-handling middleware like other middleware, except with four arguments instead of three, specifically with the signature (err, req, res, next)):

    app.use(function(err, req, res, next){
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

http://expressjs.com/guide/error-handling.html