Another case to consider is what is expected when following relations. For
artist.getPaintings()... should we include the painting which is currently
being created? Consistency is important.
Use cases are simple. Imagine a view where you show a user's widgets. They
might be mailing list subscriptions, invoices, enrolments or paintings. The
view allows you to add new items, but you haven't yet hit save at the bottom.
When you draw the view, you need to easily show ALL items, both from the
database and from memory.
This was such a common use case for us, that we intercept every SelectQuery in
our applications and add to the result items from the context. Easy to do, but
cleaner if this was in Cayenne. This sort of validation is also quite common:
throw validation exception if ( class.max() < class.getEnrolments().count() )
Ari
On 7/11/12 6:41pm, Andrus Adamchik wrote:
Agreed - should be possible to do it for SelectQuery, as it is essentially a
single-entity filter. Will require closer look at Expression.filterObjects(..)
to make sure it works for to-many, etc…
And yes - some decisions are needed on how to handle uncommitted modified and
deleted objects. It is hard for me to judge what's the best approach with
those, as honestly I've never had a scenario where I would care to fetch
against uncommitted objects. Would be great if someone could share their
typical use cases.
Andrus
On Nov 7, 2012, at 2:48 AM, Aristedes Maniatis <[email protected]> wrote:
Yes, that's what I was thinking. As you say, should be easy to implement for
the SelectQuery case. It would:
* Remove objects in the context which no longer match the query
* Add additional objects from the context (either new or edited) which match
the query
It would either throw an exception or fail silently if the query was unable to
be evaluated in memory. Not sure which is better.
Ari
On 7/11/12 8:43am, John Huss wrote:
You could just support SelectQuery fairly easily though, couldn't you?
Project Wonder has this - you can do
fetchSpec.setIncludeEditingContextChanges(true).
On Tue, Nov 6, 2012 at 3:22 PM, Andrus Adamchik <[email protected]>wrote:
On Nov 6, 2012, at 11:58 PM, Aristedes Maniatis <[email protected]> wrote:
Andrus, I wonder if there is some way to make this common use case
easier?
The only way is to implement full in-memory query evaluation.
Andrus
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Aristedes Maniatis
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Aristedes Maniatis
GPG fingerprint CBFB 84B4 738D 4E87 5E5C 5EFA EF6A 7D2E 3E49 102A
