Re: [hibernate-dev] Possibly interesting use of Jandex
On 11 March 2014 10:59, Gunnar Morling <gunnar(a)hibernate.org> wrote:
2014-03-09 18:31 GMT+01:00 Steve Ebersole
<steve(a)hibernate.org>:
@Entity
> interface Employee {
> ...
> }
>
> 2) We'd dynamically generate a class to back this. This generated class
> can contain many of the performance tweaks we've been developing via
> bytecode extensions (inline dirty-checking, "entity entry" info, etc).
>
In which situation would one make use of this? This seems to encourage
"anemic data models", i.e. entities which are just data holders but don't
contain any business logic. Often it's very useful though to add logic
dealing with an entity's state to the entity type itself.
I actually see this going in the opposite direction. Allowing to move
all the mapping stuff to a different interface would encourage me to
think of the implementation as something which can include code, and I
could even have multiple types having different *implementations* if
the non-persistent methods.
It would also fight usage of inheritance, which is common among JPA
users and something that I'd gladly avoid.
Would be a very nice to have to avoid anemic data models.
Will the class be generated at build or runtime? In case of the latter, how
would one instantiate such entity?
On a somewhat related note, I've been contemplating the notion of
"partially mapped entities" in OGM [1]. Those would provide explicit
properties only for some attributes (common ones, or ones which business
logic relates to), while others would be exposed via a generic map
structure:
@Entity
public class Product {
@Id
private long id;
private String name;
private BigDecimal price;
@AdditionalProperties
private Map<String, Object> additionalProperties;
// ...
}
This would be very beneficial for NoSQL use cases where you want to pass
through data from the store to a GUI in a generic manner or during
prototyping/rapid development, where you manifest more and more attributes
as explicit properties, just as business logic requires it.
--Gunnar
[1] https://hibernate.atlassian.net/browse/OGM-470
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