[aerogear-dev] Server Side: Paging API with Metadata and Links (was: Re: Paging Demo)

[Daniel Bevenius]

>Have you researched on using CDI interceptors for this?
No, I've not looked at a solution that involved CDI interceptors for this.

>So what about injecting pagination info via CDI?
I think that it makes sense for users to be able to simply use their
existing classes with AeroGear Controller by configuring their routes and
not have to touch existing code. This is what I liked about liked with
Bruno's suggestion. Using any of the suggestions here, and my previous
suggestion with having a specific response type, all have this
disadvantage. But this might just be wishful thinking and we might simply
discover that this is required when more functionality is added hence might
as well do this now.

>Another option would be to have the method receiving the PaginationInfo
>parameter, which would eliminate the need for annotations and stuff - if
>you put the parameter on the signature, the response will be wrapped
>automagically.
I that case I think it makes more sense to go with a solution of having a
specific return type on the method. The information in PaginationInfo would
already be available to the target endpoint methods as parameters
(offset/limit) and it would use something like was suggested earlier in
this thread. I just think that might be more clear about what is actually
going on.

I'll start looking into using an CDI interceptor solution and see how this
would work. I'll also take a look at the other approach with using
PaginationInfo. As we don't have much time here it would be great if we as
a team can decide on one solution by the end of today (2012-0122).

>We already got rid of total :)
Glad to hear that :)






On 22 January 2013 00:04, Douglas Campos <qmx at qmx.me> wrote:

> On Sun, Jan 20, 2013 at 07:29:41AM -0800, danielbevenius wrote:
> > I've been thinking about this and needed to make an update to the
> controller
> > as I hade neglected to support returning query parameters in link
> headers,
> > other than those used for paging.
> >
> > I've looked into Bruno's original suggestion and think it has a huge
> > advantage in that the target endpoint class does not have to be changed,
> and
> > can simply return a List<?>.
> >
> > route()
> >       .from("/cars")
> >       .on(RequestMethod.GET)
> >       .produces(MediaType.JSON)
> >       .paged().offset())
> >       .to(Cars.class).findCarsBy(param("offset", "0"), param("color"),
> > param("limit", "10"));
> >
> > For cases where the parameters 'offset' and 'limit' are named differently
> > they could be configurable:
> > route()
> >       .from("/cars")
> >       .on(RequestMethod.GET)
> >       .produces(MediaType.JSON)
> >       .paged().offset("myoffset").limitParamName("mylimit")
> >       .to(Cars.class).findCarsBy(param("offset", "0"), param("color"),
> > param("limit", "10"));
> Well, I'm not a fan of putting the pagination info on the routes
> themselves. Have you researched on using CDI interceptors for this? as
> it's clearly an infrastructure concern.
>
> So what about injecting pagination info via CDI? This means that we'll
> need to use instance variables on the Controller class, and decorate it
> during instantiation. The paging support could be enabled by using an
> annotation on the controller method (@Paginated), and the CDI extension
> would take care of wrapping the response/putting the headers
> accordingly.
>
> public class Cars {
>
>         private PaginationInfo paginationInfo;
>
>   @Paginated
>         public List<Car> list() {
>                 // fetch offset/limit from this.paginationInfo
>         }
> }
>
> The response would be decorated with the appropriate links.
>
> Another option would be to have the method receiving the PaginationInfo
> parameter, which would eliminate the need for annotations and stuff - if
> you put the parameter on the signature, the response will be wrapped
> automagically.
>
> Thoughts?
>
> > For now, I've just ignored support for a total as I think we need more
> time
> > to investigate a proper solution for it, if we think it should be
> supported
> > at all. The problem with having a callback is that in some situations,
> like
> > the one above, that callback would also have to take a query
> parameter(s) so
> > we'd need to do more work that like it initial idea were it would be
> > possible to simply specify a name of a no-args method that returned an
> > int/long.
> We already got rid of total :)
>
> -- qmx
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