Inheritance can vastly improve the features of EOF if used properly.
In general, I usually make all super-entities abstract, and have a
different table for each leaf. However, if your data is all the same
and you just need inheritance for different behavior in code, I
typically use a single table and use well defined qualifiers for the
entities. A while ago (after much complaining), the EOF engineers
worked out a way to not do queries for all the sub-entities if you're
entity qualifier was straightforward like: "type = 'A'". I highly
suggest sticking with this for performance reasons.
Ken
On Apr 27, 2006, at 1:00 PM, Chuck Hill wrote:
On Apr 27, 2006, at 1:13 AM, Paul Lynch wrote:
You may want to use entity inheritance to design your model; see
http://developer.apple.com/documentation/WebObjects/UsingEOModeler/
7ModelingInheritance/chapter_7_section_1.html
The only thing I'll add is that, from experience, most of the
times that using inheritance is possible, I choose to flatten out
the model instead. Other people may have different experiences.
From the OO viewpoint, a complex design has the same problems as
overnormalisation has in relational database design.
On the other side of this fence, I use inheritance whenever it
makes sense in the OO view. I have found that this greatly
simplifies many aspects of the application.
Chuck
--
Coming in late 2006 - an introduction to web applications using
WebObjects and Xcode http://www.global-village.net/wointro
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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