I think what Gili is trying to accomplish is a more
robust mechanism for defining cascading deletes.
As far as I know, what he is describing is not
supported by Cayenne (and I would be impressed if
any ORM supported it). What he is describing seems
to be a way to define and resolve delete dependencies.
What he wants is a way to define a cascade direction
(already supported by Cayenne)
i.e.
delete(grandparent [A]) cascade delete(parent [B]) cascade delete(child [C])
But he also wants to define delete dependencies.
(As far as I know, not supported by Cayenne)
So he wants a way to tell cayenne NOT to allow the deletion of
[C] records that have [A] records related indirectly to them via [B]
I believe this is what he was talking about in his first post,
then in the second post he described an algorithm for resolving
nested dependencies so his feature would work.
Correct me if I mis-understood you Gili.
Correct me if Cayenne supports this somehow [usergroup].
Sounds like a useful feature (I do this in my business logic right now)
Filip
On 9/16/05, Cris Daniluk <cris.danilu..mail.com> wrote:
> Now I'm really confused... what the hell is C? :)
>
> Are you using a join table? If so, are you using flattened
> relationships? Please describe the problem in detail. I think what you
> want to accomplish is perfectly doable, but its hard to tell with what
> you've given.
>
> On 9/16/05, Gili <cowwo..bs.darktech.org> wrote:
> >
> > I'm setting DENY in the modeler. What I am trying to communicate to
> > Cayenne is that it is all right to delete(Master) -- this should trigger
> > the deletion of all children -- but it is not alright to delete(Child).
> >
> > If I have:
> >
> > - A -> B -> C (cascading delete)
> > - C is set to DENY if any instances of A are referencing it
> > - User deletes A
> >
> > then I expect it to work because A is saying "I'll delete my reference
> > to C if it'll let me delete it" and that should be quite all right.
> >
> > Gili
> >
> > Cris Daniluk wrote:
> > > On 9/15/05, Gili <cowwo..bs.darktech.org> wrote:
> > >
> > >>Hi,
> > >>
> > >> I've got this relationship:
> > >>
> > >>On delete of A, cascade to B
> > >>On delete of B, if any "A" instances exist, DENY
> > >>
> > >> What I'm seeing at runtime is that I delete A, it tries to cascade to B
> > >>but this fails because A is still associated with it. Cayenne doesn't
> > >>seem to be smart enough to notice this is ok because A is the one
> > >>triggering the delete in the first place. Here are the logs I get at
> > >>runtime (I added these to the code):
> > >
> > >
> > > When you say DENY, are you referring to how you have it set up in the
> > > Modeler, or in the database? Are you sure you don't mean to have "No
> > > action"?
> > >
> > > If you use a master/child relationship, it sounds like you're doing:
> > >
> > > delete(Master) => delete(Children)
> > >
> > > delete(Child) => deny
> > >
> > > But that doesn't make a whole lot of sense... alternatively, you might be doing:
> > >
> > > delete(Child) => delete(Master)
> > >
> > > delete(Master) => deny if children
> > >
> > > Again, not making a whole lot of sense to me. I am probably not quite
> > > getting what you're trying to do here, but it sounds like Cayenne is
> > > doing the right thing. You generally want to pair a cascade and no
> > > action, not a cascade and deny.
> > >
> > > Cris
> > >
> >
> > --
> > http://www.desktopbeautifier.com/
> >
>
This archive was generated by hypermail 2.0.0 : Fri Sep 16 2005 - 13:45:09 EDT