[seam-dev] To cascade or not...

[Max Rydahl Andersen]

Convenient does not mean it should be default.

Anyway, for GA we will keep the "old" default since it was discovered 
too late.

Then when we do have the ui for controlling the default I would just 
have a few options but
let none be the default since it is the less risky one and you can set 
the default option in persistence.xml
instead of going set it on every single entity.

/max
> On Wed, Mar 4, 2009 at 2:59 PM, Emmanuel Bernard 
> <emmanuel at hibernate.org <mailto:emmanuel at hibernate.org>> wrote:
>
>     class Address {
>       @ManyToOne Country country;
>       @ManyToOne State state;
>       @ManyToMany Set<Person> inhabitants;
>     }
>
>     It generally makes no sense to cascade persist for these three
>     associations. Even if your app has 80 entities, it's very likely
>     that half of the associations should not be cascaded :)
>
>     Let's take your proposal
>     PERSIST, DELETE, REFRESH
>
>     I REFRESH address and changes on Person are lost, doh!
>
>
> True. I was on the fence about REFRESH. I think you convinced me.
>
>     PERSIST, do I really save an address and expect the person living
>     there to be added to the system. Surely not, the person is very
>     likely to have been built beforehand. Same for Country and State.
>
>
> Not a problem if County and State are managed, which is likely how you 
> attach them anyway. It will even work if they are a non-managed entity 
> with a valid ID. If neither of those are the case, then yes, I want 
> the persist to add them to the database. That's the whole point of the 
> cascade.
>
>     MERGE Do I really want to update a country when an address
>     changes? I can't find a system that would do that.
>
>
> I don't do MERGE, so I don't care.
>
>     Cascade has performance consequences. The more cascades the slower
>     your app will be at flush time. Especially on applications with a
>     lot of entities.
>
>     NONE is a good default, that's why it's the default we have chosen :)
>
>
> I'm still don't agree. I like PERSIST and DELETE. DELETE can be 
> dangerous, but it's also extremely convenient.
>
> -Dan
>
> -- 
> Dan Allen
> Senior Software Engineer, Red Hat | Author of Seam in Action
>
> http://mojavelinux.com
> http://mojavelinux.com/seaminaction
>
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