On Monday, June 27, 2011 12:40:05 PM UTC+2, Ryan McFall wrote:
>
> I have two domain objects that implement the same interface on the
> server, and a third class that contains a (heterogeneous) List of
> those objects. I need to be able to expose this list on the client
> side. The domain objects do not share a common super-class (they
> instead delegate the common functionality to another object).
>
> Given that all proxy interfaces are required to extend BaseProxy, I
> cannot figure out how to write multiple proxies that will have a
> parent interface in common. I tried making a base interface that both
> proxies extend, but that base interface must extend EntityProxy, and
> the GWT compiler complains if you have an interface that extends
> EntityProxy but does not have a ProxyFor annotation.
>
The interface need not extend EntityProxy, you can have:
interface BaseInterface { ... }
interface FooProxy extends BaseInterface, EntityProxy { }
interface BarProxy extends BaseInterface, EntityProxy { }
...but then you obviously cannot have a proxy declare a list that contain
both FooProxy and BarProxy, as a Collection<BaseInterface> would be rejected
because BaseInterface doesn't extend EntityProxy or ValueProxy.
BUT!
- The hierarchy of proxy interfaces need not mimic the one of domain
objects on the server-side. You could have "interface BarProxy extends
FooProxy" for example.
- or, because you can have more than one proxy interface for the same
domain object, you could annotate the base interface with a @ProxyFor for
one of the domain class.
I am wondering (although I suspect the answer is no) whether I can
> have a single interface declare that it is a proxy for multiple
> entities. If not, other ideas for making this work are welcome.
You're right: an interface can only map to a single domain class. Moreover,
you cannot use an interface in a @ProxyFor, as the
RequestFactoryInterfaceValidator used by the RequestFactoryServlet will
ultimately flag it as an error (so you unfortunately cannot use the
interface implemented by both your domain objects).
RequestFactory does not
(yet<http://code.google.com/p/google-web-toolkit/issues/detail?id=5367>)
support polymorphism, so your collection can only ever contain a single
"interface".
Not sure there's a solution to your problem besides refactoring your domain
classes (but maybe if you share a bit more information, maybe there's a
solution)
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