On Apr 1, 2008, at 8:41 PM, Andrew Lindesay wrote:
Hello Jeff;
I've decided to fully EOize my app to replace my current use of
flat files, mainly to better deal with concurrency issues. In
creating my analogous tables, I found that there's no way to
specify a "1 to 1" relationship between tables using the Entity
Modeler tool. Is there a specific reason for this? Or is it just
figured that you might as well make it one to many anyway even if
it is just one to one?
"You can't really do that" :) However if you make a 1:M
relationship you can add an accessor-method which just makes the :M
a :1 or throws a runtime exception if it find a :M with more than
one element in it. On the very rare occasions where a 1:1 has made
any sense, I have done this.
I am pretty sure that you can, if you join them on the PK. This does
require you to "propagate primary key".
If you're wondering why I want to do this, it's to hopefully reduce
conflicts of multiple people updating the same record in a table.
Is that generally a good reason to split 1 to 1 data into two tables?
Are you looking to prevent optimistic-locking-on-write conflicts?
Perhaps it would be better to implement a change-notification system
to keep the data fresh in the instances?
That won't prevent optimistic locking conflicts, just reduce how often
they occur. You still need to handle them.
Chuck
--
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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