How to use streamlinejs in expressjs?

Question

How to use streamlinejs in expressjs?

When I use expressjs, but I don't know how to use it with streamlinejs.

Look at the express code:

var app = express.createServer();

app.get('/', function(req,res) {
   User.find({name:'Jack'}, function(err, users) {
      res.send(users);
   });
});

How to use streamlinejs in the code?

node.js
express

Answer 1

That's a point I'm covering quickly in the FAQ (https://github.com/Sage/streamlinejs/blob/master/FAQ.md#the-underscore-trick-is-designed-for-callbacks-but-not-events-how-do-i-deal-with-events).

The easiest solution is to add the underscore as extra parameter to the get callback:

app.get('/', function(req,res, next, _) {
   var users = User.find({name:'Jack'}, _);
   res.send(users);
});

The only problem would be if connect adds a fourth parameter to its callback some day. The following is a bit safer (but probably overkill because I don't see why connect would change its callback API):

app.get('/', function(req,res) {
   (function(_) {
      var users = User.find({name:'Jack'}, _);
      res.send(users);
   })(trap); // trap is a generic callback that handles errors
});

Answer 2

We use Express and Streamline for The Thingdom, and to do that, we built a simple wrapper that allows the next callback (third parameter) to be a Streamline-friendly callback, for both route handlers and middleware handlers.

Here you go:

https://gist.github.com/1087991

=)

~~I've been meaning to make that into a generic module and publish to npm -- I'll do that soon.~~ Edit: https://github.com/aseemk/express-streamline

Note that there is one trade-off as a result of this -- you can't have route handlers "continue" (fall through) to other route handlers. We've never used that feature, though, and don't foresee ourselves doing so -- it's much simpler to know that every route handler is the final destination -- so we were okay with that trade-off.

Edit: This is only tested with Express 2.x.