Re: Setting up horizontal inheritance
Re: Setting up horizontal inheritance
- Subject: Re: Setting up horizontal inheritance
- From: Chuck Hill <email@hidden>
- Date: Tue, 4 Nov 2008 11:42:52 -0800
On Nov 4, 2008, at 11:37 AM, Lachlan Deck wrote:
On 05/11/2008, at 6:25 AM, Lachlan Deck wrote:
On 04/11/2008, at 8:50 PM, Paul Hoadley wrote:
I have another clue. Thanks for bearing with me.
On 04/11/2008, at 6:27 PM, Paul Hoadley wrote:
Maybe I need to start again from scratch.
Just to recap:
1. I have a framework that contains a model Auth that contains an
entity Person. It also contains the UserPreference entity that
has a to-one relationship to Person. Person is abstract.
2. I have an app that contains a model AMAuth that contains an
entity AMPerson. I created AMPerson by subclassing Person in the
Auth model (nominating HI), and then cut + pasting over the
entries for AMPerson in index.eomodeld, and AMPerson.plist to the
AMAuth model. I changed the package on the class appropriately.
(Is there an easier way to generate a cross-model sub-entity?)
3. I have set up the tables using the SQL generated by Entity
Modeler. This creates both 'person' and 'amperson',
That is not horizontal inheritance to my understanding. You have
Vertical inheritance and so you've not modelled it correctly.
Person should not have a table for Horizontal.
So Chuck says for Frontbase "It does for FrontBase as the PK
generation sequences as associated with a physical table in
FrontBase. ". That's puzzling to me. i.e., AMPerson is a physical
table. Why does the parent need to map to a physical table at all
for HI?
Or are you saying for HI that the pks are sequential across sub-
entities for frontbase?
He's using postgres however...
The PK must be unique (not sequential) across ALL objects in an
inheritance hierarchy. All. For HI, this means that two tables in
the hierarchy can NOT have a row with the same PK. EOF generates all
PKs for all objects in an inheritance hierarchy from the sequence
associated with the base / root entity.
Chuck
--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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