getReferrers doesn't return non-persisted documents

[dantleech]

When calling $documentManager->getReferrers() only persisted referrers are returned.

Should we expect this to return managed but non-persisted documents too?

[dbu]

we had this and once said we want not attempt to do it. http://www.doctrine-project.org/jira/browse/PHPCR-106

i see your usecase, but i really don't know how we could reliably do that. assume i have A referring B. i do A->add(B) and then getReferrers(B). the UoW would have to check all managed documents if they got new refererences. with a larger document set, this is just going to be a killer.

[dantleech]

Wouldn't we just to have to lookup the class metadata when we add document A / B to the manager and build up a referrers map? I don't think that would be a big killer .. or would it?

[dbu]

assume A has a reference mapping to B. now i load 50 documents of type A from storage and on one of them, add a reference to one of the B. now i ask for the referrers of that B. i have to check all 50 A to know if there is a change on any of them, and if so look if they start pointing to B. as we still would also query phpcr, we would then have to figure out which references are new. to make it even more fun, i could also have an unflushed removal of a reference...

[dbu]

@dantleech are you ok if we say this is not going to happen? btw. i think even after the flush the collections won't automatically be updated, you would have to refresh them manually.

[dantleech]

Hmm, yeah I can see it is tricky. I was thining we could use the Proxy architecture to register when a class adds a reference, but then that would only work on documents which have been loaded from the system.

Ideally speaking, I think this would be a nice to have -- an ORM is supposed to persist object relations, so the "relationship" management should probably happen in userland.

But yeah, fine with calling this a non-feature for now.

[dbu]

doctrine orm handles it like this: there is an owning side of a relation. when you add something to that side, its the job of your model to update the non-owning side. for us, that would mean to propagate on addChild a call to setParent($this) to the added child resp. doing $parent->addChild($this) on setParent in a child. the same for referrers and references. but this is a model level job, not something doctrine can do for the user.

not sure if this would currently all work, or if we would try to persist something twice. the tricky part is that contrary to orm, phpcr-odm documents do not necessarily know the class of the other side, so they don't know what method to call. it would require some instanceof checks with the HierarchyInterface for example.

if you go directly to the db it won't see it, which makes sense.

[lsmith77]

is this now fixed via #514?

[dbu]

nope, its that $dm->getReferrers($document) goes to the db only and does not look at in-memory state. i am arguing that its basically impossible to get this right in a performant way.

[lsmith77]

yeah .. imho we should close this ..

[dantleech]

closing...