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Re: entity inheritance possibilities
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Re: entity inheritance possibilities


  • Subject: Re: entity inheritance possibilities
  • From: Ben Trumbull <email@hidden>
  • Date: Mon, 8 Sep 2003 12:00:48 -0700

At 13:35 -0500 9/8/03, Jonathan Rochkind wrote:
Especially since the horizontal inheritance I'd end up with is somewhat buggy anyway.

Well, if it's a copy of the tables, it can be single table or vertical inheritance just as easily.


A) The psuedo to-one 'relationship' can't be established until the destination is committed to the db.

Sure it can. Listen of the GIDChanged notification. Think like a union in C, either a pk-entity or a temporary GID. You'll want a direct reference to the object in the same EC.


You will not get the GIDChanged notification until after the save.

But the first two are. Any ideas there?

If you need first class relationships with all the functionality EOF provides, then rewriting a relationship yourself in business logic is not going to cut it.


The business logic approach works well for EOs which simply need a reference to a set of other EOs. A looser connection than an actual relationship.

2) Only one of them will actually be valid; which one is valid is determined by the 'entityName' attribute, and we can use business logic to address the proper one.

It may mostly work. It will defeat prefetched keypaths and generally make life more complicated. The EOModel will not represent the actual object mapping, which may be confusing later. If this pattern is widely used, it will impact memory consumption.


If anyone can follow all this and understand what I'm talking about... any ideas or suggestions?

Take your medicine now, don't create a maintenance nightmare later. Hack the PKs or export to XML, or whatever. Begin next week with something "normal".


Or don't do it at all. Your app works now, so maybe this problem doesn't need to be solved. Maybe there are alternatives to changing the entity relationships.
--


-Ben
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