Andrus Adamchik commented on CAY-1008:
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The example is clear. This is what I called "redundant" relationships in our mailing list discussion that followed from the related set of Jiras including this one. (I don't remember what we decided to call "redundant" to avoid implying a negative meaning)... Anyways, Cayenne will not maintain the object graph consistency if there are multiple relationships between 2 entities, spanning the same set of joins. Right now that's more of a "feature" than a "bug" IMO (ok, maybe a "limitation" coming from the fact that the authors originally didn't find use for such relatinships themselves), but we can impement an algorithm that will handle such case as well.
> Reverse relationships may not be correctly set if inheritance is used.
> ----------------------------------------------------------------------
>
> Key: CAY-1008
> URL: https://issues.apache.org/cayenne/browse/CAY-1008
> Project: Cayenne
> Issue Type: Bug
> Components: Cayenne Core Library
> Affects Versions: 3.0
> Reporter: Kevin Menard
> Assignee: Andrus Adamchik
>
> Given two entities, Employee and Address, such that there is a one-to-many relationship between the two, it may be possible that reverse relationships are not fully set if inheritance is used.
> For example, let's say that HomeAddress extends Address, then the following fails:
> Employee e = context.newObject(Employee.class);
> Address a = context.newObject(Address.class);
> a.setToEmployee(e);
> assertEquals(1, e.getAddresses().size());
> assertEquals(0, e.getHomeAddresses().size());
> HomeAddress ha = context.newObject(HomeAddress.class);
> ha.setToEmployee(e);
> assertEquals(2, e.getAddresses().size());
> assertEquals(1, e.getHomeAddresses().size());
> The last assertion fails as e.getHomeAddresses() will return an empty list.
> On the face of it, the problem is that the ObjRel "addresses" is being set rather than "homeAddresses". This is due to how ObjRelationship#getReverseRelationship() determines reverse relationships. It does so by inspecting the relationship structure and if there's a match, returns it. "addresses" and "homeAddresses" have the same structure and "addresses" is the first match found and returned.
> Simply reversing order or other similar tricks won't really do anything more for us though. The real issue seems to be how to deal with multiple ObjRels that match to the same DbRel. Each ObjRel does need to be updated in order for the graph to remain consistent.
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