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From David Bullock ...@dawnbreaks.net>
Subject Re: Issue 150: Consistency requirements for relationships with mapped-by
Date Thu, 22 Dec 2005 10:46:59 GMT
Craig L Russell wrote:

> The "in your face" issue I'm wrestling with is the inconsistency in 
> the specification where we say that changes are ignored if made to the 
> "mapped-by" side and also that changes made to the memory model are 
> visible after commit.
> [...]
> It's evident to me that it's possible to detect changes to either side 
> of the relationship and make the two sides consistent.
> [...]
> I don't think that it makes sense for JDO that users' model changes to 
> be ignored just because they happen to be made to the "wrong side" of 
> the relationship.
> [...]
> 3. Inconsistencies should not be accepted, as they indicate user code 
> gone bad.


We're mostly in vehement agreement, especially about not ignoring the 
user's assignments to fields.  I think your proposal is certainly a 
clarification and improvement.

It's just that I would include 'stupid user only updated one side of the 
relationship' as one of the inconsistencies that causes a 
JDOUserException to be thrown at commit.  Instead of the JDO runtime 
'fixing' the other side as a convenience.  I don't want that 
convenience. If I've failed to update both sides of a relationship, that 
could easily have implications for the correctness of my code before 
commit, and I don't want JDO to silently fix things - I want to know. 

"Please force me to update both sides", is what I'm saying.  I don't 
know who is demanding that users be allowed to only update one side of 
the relationship.  Sure, I'd like that feature IF the update happened 
immediately as per managed relationships.  But fixing my model after 
commit doesn't help me before commit, so you might as well make me do 
things manually (which is a coding obligation that I already have when 
not using persistence).

So rather than new features I'm asking you to be more stringent!

cheers,
David.


PS.  The updated text is more clear, thanks.

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