Re: Unique ID without create entity?
Re: Unique ID without create entity?
- Subject: Re: Unique ID without create entity?
- From: Guido Neitzer <email@hidden>
- Date: Sat, 4 Oct 2008 12:15:36 -0600
On 04.10.2008, at 02:11, Yung-Luen Lan wrote:
Thanks for your suggestion. Could you elaborate more? Why is using PK
considered as a bad style?
A pk or fk is organizational information for the database that has no
meaning for an actual data object in Java land. If you introduce a
meaning, e.g. use this information for something in Java land, you are
mixing organizational with actual information.
Unfortunately I do the same in some instances, but this is because I
didn't know better when I created the model years ago.
If for whatever reason you need the pk before saving an object, you
can use a Wonder feature "primaryKeyInTransaction" (careful, that
doesn't work with child editing contexts), where you get the pk before
the object is saved to the db. But with that hint, I only give you the
gun to shoot yourself in the foot. I do not, really do not, recommend
doing this.
I started using EOF byte[24] keys a while ago to prevent myself from
using pks for anything else. These can have other problems (database
and indexing related, if your database is not very fast indexing
tables on these keys), but they help seeing the relational information
as nothing else and to avoid touching it.
cug
--
Real World WebObjects Bootcamp at the Big Nerd Ranch:
http://www.bignerdranch.com/classes/real-world_webobjects.shtml
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