play framework - what is the proper way to return list of data? - scala

Question

I'm new to the reactive/observables concept.
I've defined a route for getting Products like this:
GET /products controllers.ProductController.findProducts
and the implementation in the controller:
def findProducts() = secured.async { implicit request =>
productDao.find()
.map(products => Ok(Json.toJson(products)))
// products: List[Product]
.recover(errHandler)
}
Then, on the client-side, I'm making the call and subscribing to it like this:
let sub = this.find()
.subscribe(
products => {
this.products = products;
this.productsBehaviorSubject.next( this.products );
if (!!sub)
sub.unsubscribe();
},
error => console.log("Error fetching units: " + error)
);
As soon as I get the data, I unsubscribe from it. (basically using it like Promises).
So I wonder, if this is the right way to do it. Instead of returning List[Product] in one single response, should I be returning in several responses??
def findProducts() = secured.async { implicit request =>
productDao.find()
.map(products => {
products.map(p => Ok(Json.toJson(p))) // haven't tried this yet
})
// products: List[Product]
.recover(errHandler)
}
then on the client side .. maybe .:
this.find()
.take( 50 )
.subscribe(
product => {
this.products.push( product )
},
error => console.log("Error fetching units: " + error),
() => this.productsBehaviorSubject.next( this.products )
);

Answer 1

Your first approach is correct, you will notice that the secured.async expects the code block to return Future[Result]. So if you try to map over the products then the signature will be Future[Seq[Result]] which will give you a compilation error.
Also in my experience, returning the full list in a single response is the standard way to code.