Include body params on request logging about express-winston-middleware HOT 5 OPEN

@zianwar -- You can start with the canned middleware: https://github.com/FormidableLabs/express-winston-middleware/blob/master/examples/server.js#L22-L25 and then augment custom middleware like in https://github.com/FormidableLabs/express-winston-middleware/blob/master/examples/server.js#L32-L37 to add extra metadata.

So something like

// Middleware automatically adds request logging at finish of request.
app.use(winMid.request(logOpts, {
  type: "per-request-log"
}));

// Also inject extra metadata into the log object.
app.use(function (req, res, next) {
  // Add anything you want right here!!!
  res.locals._log.addMeta({
    // Req object already exists. This object will get deep-merged
    req: {
      body: req.body
    }
  });

  next();
});

The above pattern of later addMeta calls works because the actual request log event isn't issued until the response is actually sent. So you can repeatedly addMeta() in any handler!

Also, I should note that res.locals._log in this context is a per request instantiated log object. So any metadata added in addMeta calls will get logged out for any other manual calls like res.locals._log.info() in your handlers.

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thank you @ryan-roemer this worked as expected!
I still have 2 questions,

1. How can I log the response body?
2. Is it possible to remove some meta from the request? maybe some function like removeMeta ?

from express-winston-middleware.

Hi @zianwar

1. In my example you'll note you have access to the res object. You can add anything you like from that too.

2. For removing meta, there isn't something straight up.

   a. But if you look at the source of addMeta (https://github.com/FormidableLabs/express-winston-middleware/blob/master/index.js#L298-L310) you'll note there is a _.merge() of the new object you provide. This means if you pass in something like { req: null } it should should nuke that entire field. This isn't a complete solution obviously as you may want just some of an existing field. But it works right now...
   b. or you could directly access the private member variable res.locals._log._meta which may break in the future, but works in a pinch now.
   c. I would accept a PR for this lib with something like transformMeta(function (oldMeta) { return newMeta; }) (or maybe an async version.

Hope that helps.

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Hey @ryan-roemer, thank you for this detailed reply.
Although I've managed to edit meta, I'd like to improve the library by submitting a PR as you said in (c).

What do you think of something simple like this?

Log.prototype.transformMeta = function (transformer) {
  this._meta = transformer(this._meta);

  return this;
};

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@zianwar -- Looks good! Let's name the transform function fn per our collection of project usual conventions.

Thanks!

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