How can I use express router routes for dual use? - node.js

Question

So I have a node app using express router and routes, for example I have a router that handles fetching company objects from the database, within the Company router the get method looks like this:
router.get('/:id', function(req, res, next) {
var id = req.params.id;
models.Company.get(Number(id), function(err, entity) {
if (err) {
console.error("Get error:", err);
}
console.log('Got entity:', entity);
req.data = entity;
next()
});
});
Now if I am in another router, say the Reviews router and I want to get a company I would like to be able to call this route in order to grab that company, instead of having to duplicate code.
How do I do that?

Answer 1

You can either use a named function, if you really want to use the same handler:
function yourHandler(req, res, next) {
var id = req.params.id;
models.Company.get(Number(id), function(err, entity) {
if (err) {
console.error("Get error:", err);
}
console.log('Got entity:', entity);
req.data = entity;
next()
});
}
router.get('/:id', yourHandler);
router2.get('/companies/:id', yourHandler);
Or you can abstract away only the actual database lookup, by making a function that takes a callback:
function getCompany(id, callback) {
models.Company.get(Number(id), function(err, entity) {
if (err) {
console.error("Get error:", err);
callback(err);
} else {
console.log('Got entity:', entity);
callback(null, entity);
}
});
}
or a function that returns a promise:
function getCompany(id) {
return new Promise(function (resolve, reject) {
models.Company.get(Number(id), function(err, entity) {
if (err) {
console.error("Get error:", err);
reject(err);
} else {
console.log('Got entity:', entity);
resolve(entity);
}
});
});
}
The difference is that you use the callback-taking version like this:
getCompany(123, function (err, data) {
if (err) {
// handle error
} else {
// you have data
}
});
and you use the promise-returning version like this:
getCompany(123)
.then(function (data) {
// you have data
})
.catch(function (err) {
// handle error
});
The callback versions are easy to compose using the async module and the promise versions are easy to compose using the bluebird module or some other promise framework. See:
http://caolan.github.io/async/
http://bluebirdjs.com/
It's also worth mentioning that Bluebird is much faster than native ES6 promises, see this answer for details.