If you familiar with how EOF works, it propagates object updates among
EOEditingContexts within the same JVM, but not accross JVMs. For me (and I
believe for others too) this was a source of many problems.
So at the early design stages we made a deliberate decision to exclude
update notifications from Cayenne, until we implement a mechanism that
handles it the same way for both local and remote DataContexts.
Now I hope the time is approaching when we are ready to start solving this
problem (see recent Holger's messages on this topic). This is still in the
design stage though... So current DataContext is always an isolated view of
the data.
Andrus
Dave Paules writes:
> Hi list,
> I was using Cayenne the other day and I didn't see an elegant way for
> recognizing when another user has made changes to the same object I have
> changed.
>
> Let's use an example:
>
> I have a Person entity with firstName and lastName attributes.
> The instance in question has the values "Dave" and "Paules" respectively.
>
> user1 and user2 have both fetched the Person instance Dave Paules.
> Let's say user1 changes the firstName attribute from "Dave" to "dave". He
> commits his change.
> Meanwhile user2 decides to change the lastName attribute from "Paules" to
> "PAULES".
>
> After committing his change to lastName, user2 will not see user1's
> firstName change once his commit has successfully completed. user2, even
> thought he was making changes to an object, and that object needs to be
> reconciled with the database (or at least the ObjectStore's snapshot), it is
> not.
>
> user2 believes after his commit that the Person has values "Dave" and
> "PAULES". In reality, the ObjectStore and the database have the correct
> values: "dave" and "PAULES".
>
> Why is user2's object not updated first from the ObjectStore's snapshot
> during a commit, and then his changes applied on top of this most recent
> view?
> Perhaps this cannot be done for toMany relationships, but it should be
> possible for 1:1 and local persistent attributes of the object.
>
> What are your thoughts? I think this automation is sorely missed in Cayenne.
> Does anyone know of a more elegant workaround? Any help is much appreciated.
>
> Thanks in advance
> Dave Paules
> Quantum Leap Innovations
> www.quantumleap.us
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