Re: vertical inheritance
Re: vertical inheritance
- Subject: Re: vertical inheritance
- From: Lachlan Deck <email@hidden>
- Date: Tue, 22 May 2007 05:21:33 +1000
On 21/05/2007, at 11:21 PM, Robert Walker wrote:
There is an example of all three types of inheritance models
located in /Developer/Examples/JavaWebObjects/WOInheritanceExample.
It does show examples of deep inheritance for all three types
including vertical.
I'd forgotten about that. Thanks.
Basically, I just sort of despise vertical inheritance :)
I definitely agree with you on this one. I have used it, but only
in a shallow inheritance (one level deep) and only fetching on leaf
nodes. This was also earlier in my WO days before really
understanding it's disadvantages. Although in my case I never
really ran into any particular problems with it. I got lucky in
other words.
I need it because of the need to do a many-to-many join with another
entity. It would be much messier creating joins for every entity.
On the plus side it does make for a clean database schema to
represent the inheritance, but in most cases that just not worth
the potential problems it can cause.
Such as?
Questions:
1) why do they specify 'serverTimeZone = US/Eastern;' for a number of
inherited members? Is that just an EOModeler artifact?
2) They've got 'ownsDestination = Y;' from each child to parent
relation. Mike, are you validating on this one?
3) I was getting particular problems when using prototypes rather
than, as they've done, without them. So when prototypes are in the
mix, how ought an inherited/derived member look?
4) which keys does EOF not take note of for a derived attribue
(allowsNull, etc)? i.e., when you specify a prototype which other
keys ought not be present.
with regards,
--
Lachlan Deck
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