[hibernate-dev] Hibernate Rx: Remove Optional from API

[Steve Ebersole]

Bit off track, but since you mentioned load, etc... Take a look at
the IdentifierLoadAccess, etc variants for loading.  E.g.

interface IdentifierLoadAccess<T> {
    T getReference(Object id);
    T load(Object id);
    Optional<T> loadOptional(Object id);
}

Granted I'm partial, but I think that's pretty clear :)

Reactive stuff is a bit different, but from my experience I would never
ever ever use something like `Optional<TheOtherEntity>` for an
association.  In fact back in the day this was more/less what Top Link did
for to-one mappings and it was fugly.  Not that you are suggesting that
per-se.


On Thu, Apr 16, 2020 at 9:11 AM Sanne Grinovero <sanne at hibernate.org> wrote:

> I would agree with you all about the general sentiment against the use
> of Optional, but there's one use case in which I think it might make
> sense (although bear with me as I've never really used it much yet) :
>
> there's several methods on the standard Session and EntityManager in
> Hibernate ORM to fetch a single entity: load/find/get/...
>
> Even after all these years, I always have to open the Javadoc to
> remember which ones are making assumptions about the entity existence
> in the database (so could return a proxy even if the object doesn't
> actually existin the DB), and which ones are going to check first in
> the DB, possibly returning null.
>
> Wouldn't Optional be great there to express the doubt vs the certainty
> of it returning something?
>
> Similarly in xToOne associations, having to remember to set the
> "optional" attribute, or having business code having to match the
> mapping is not ideal. That's perhaps unrelated, as this second point
> is more about how users should express mappings rather than how we
> expose APIs, but I mean it as an example to not necessarily go to the
> extreme of ignoring that it might have some use in some selected
> cases.
>
> Thanks,
> Sanne
>
> On Thu, 16 Apr 2020 at 11:44, Davide D'Alto <daltodavide at gmail.com> wrote:
> >
> > Hi,
> > Gavin sent this PR: https://github.com/hibernate/hibernate-rx/pull/93
> >
> > It removes Optional from the API, for example:
> >
> > <T> CompletionStage<Optional<T>> fetch(T association);
> >
> > becomes:
> >
> > <T> CompletionStage<T> fetch(T association);
> >
> > Is there anybody here with strong opinions about keeping Optional in the
> > API?
> >
> > Thanks,
> > Davide
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