Is there a "Caused by" for this UndeclaredThrowableException?
On Wednesday, November 28, 2012 10:41:34 AM UTC+1, Ümit Seren wrote:
>
> I am not sure if this is a known issue. But I recently tried to map some JPA2
> Entities to ValueProxy's and run into a weird issue.
>
> In the database I have a table (Term) which references itself using an
> intermediate/mapping table (basically building a graph like structure).
>
> Term ---> Term2Term.parent
> Term <--- Term2Term.child
>
> Basically a record from table A can have n childrin and exactly one parent
> (DAG).
>
> The ValueProxy's look like this:
>
>
> @ProxyForName(value="xxxxx")
> public interface TermProxy extends ValueProxy {
> public Integer getId();
> ......
> public Set<Term2TermProxy> getParents();
> public Set<Term2TermProxy> getChilds();
> }
>
>
> @ProxyForName(value="xxxx")
> public interface Term2TermProxy extends ValueProxy {
>
> public Integer getId();
> public TermProxy getParent();
>
> public TermProxy getChild();
>
> }
>
> Furthermore I have an EntityProxy in which one Term is embedded:
>
>
> @ProxyForName(xxx)
> public interface SomeEntityProxy extends EntityProxy{
> TermProxy getTraitOntologyTerm();
>
> }
>
> When I load the SomeEntityProxy object and also load the TermProxy I run
> into an infinite loop on the backend/server when serializing the payload
> with following exception:
>
> java.lang.reflect.UndeclaredThrowableException
> at $Proxy118.hashCode(Unknown Source)
> at
> com.google.web.bindery.autobean.vm.impl.ShimHandler.hashCode(ShimHandler.java:66)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:601)
> at
> com.google.web.bindery.autobean.vm.impl.ShimHandler.invoke(ShimHandler.java:76)
> at $Proxy118.hashCode(Unknown Source)
> at java.util.HashMap.hash(HashMap.java:351)
> at java.util.HashMap.put(HashMap.java:471)
> at java.util.HashSet.add(HashSet.java:217)
> at
> com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:637)
> at
> com.google.web.bindery.requestfactory.server.Resolver.access$400(Resolver.java:51)
> at
> com.google.web.bindery.requestfactory.server.Resolver$PropertyResolver.visitReferenceProperty(Resolver.java:140)
> at
> com.google.web.bindery.autobean.shared.AutoBeanVisitor.visitCollectionProperty(AutoBeanVisitor.java:229)
> at
> com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:300)
> at
> com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166)
> at
> com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101)
> at
> com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:414)
>
> I suspect that this is due to the fact that ValueProxy's don't have an
> identity and on the backend it traverse through all properties of my
> entity. However by having a reference from Term2Term back to Term I can
> end up with a cyclic dependency.
>
> i.e. Term A -> Term2Term.parent -> Term B -> Term2Term.child -> Term A
>
> If I break one of the relationships (parent or child) from Term to
> Term2Term it serializes fine. However when I adda nother ValueProxy (Term A
> -> SomeValueProxy -> Term A ) that contains a property which maps back to
> the Term, I again get a stackoverflow however this time on the client.
>
> I guess switching to EntityProxy would solve the problem as the
> properties don't automatically get serialized and for identity the
> stableId is used.
>
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