Use Async lib in nodejs - node.js

Question

Hello guys here is my code:
function get_group(req, res, next) {
var send_result = function(err, group_list) {
[...]
res.send(group_list);
return next();
};
Group.findOne({'_id': req.params._id}, send_result);
}
Now how can I implement the async library (caolan) using async.series and combine the findOne() with send_result, the code as it is look pretty disorganised to me.
EDIT1:
I used this strategy but I am not sure is correct, any suggestion?
function get_group(req, res, next) {
async.waterfall([
function(callback) {
Group.findOne({'_id': req.params._id}, callback);
}
],
function (err, group_list){
res.send(group_list);
return next();
});
}
Any suggestion?

Answer 1

For what they call routes in Express.js you actually almost never need to use the async library. The reason is that routes are actually a sort of control flow them self. They take as many middleware as you want so you can divide your routes into small blocks of code.
For example lets say you want to get one record/document from a database do something with it and then send it as json. Then you can do the following:
var getOne = function(req, res, next){
db.one( 'some id', function(err, data){
if (err){
return next( { type: 'database', error: err } );
};
res.local( 'product', data );
next();
});
};
var transformProduct = function(req, res, next){
var product = res.locals().product;
transform( product, function(data){
res.local('product', data);
next();
});
};
var sendProduct = function(req, res, next){
var product = res.locals().product;
res.json(product);
};
app.get( '/product', getOne, transformProduct, sendProduct );
If you write middleware for your routes like this you'll end up with small building blocks you can easily reuse throughout your application.