Re: Check / Force field uniqueness in EOF
Re: Check / Force field uniqueness in EOF
- Subject: Re: Check / Force field uniqueness in EOF
- From: Chuck Hill <email@hidden>
- Date: Wed, 25 Mar 2009 13:02:51 -0700
On Mar 25, 2009, at 12:59 PM, Simon McLean wrote:
might be worth checking this out - from the wonder blog :-)
ERXEOControlUtilities. validateUniquenessOf provides a utility method
for validating unique EO attribute values.
/**
*ValidateswhetherthevaluesofthespecifiedkeyPathsareuniqueforan
*Entity.Throwsa{@link ERXValidationException}ifthereisalreadyanEO
*withthesamevaluesonthegivenkeypaths.
*
*Shouldbecombinedwithaconstraintonthecorrespondingdatabase
*columns.<br />
2009/3/25 Dan Grec <email@hidden>:
Full of questions today....
I have an EO that has a field "RemoteSystemID" that must be unique
in the
DB.
I have the constraint in the DB and that works well.
What I would like, is a way in EOF to detect non-uniqueness without
going to
the db and relying on the SQL Exception.
Currently, I have something like this:
@Override
public void validateForSave() throws
NSValidation.ValidationException {
validateRemoteSystemId();
super.validateForSave();
}
//check that no Categories have this same remoteSystemID
public void validateRemoteSystemId() {
NSArray<Category> categories =
SCEOFetcher.objectsMatchingKeyAndValue(editingContext(),
Category.class,
_Category.REMOTE_SYSTEM_ID_KEY, remoteSystemId(), EOFetcher.DBEC);
if (categories.count() > 1)
throw new NSValidation.ValidationException("Category Remote
System
Id must be unique.", this, REMOTE_SYSTEM_ID_KEY);
}
This works really well if there is already one in the DB with a
value of say
"123" and I try to add with with a value of "123".
This does not work if I try to add two at the same time with a
value of
"567", it allows them both through.
Does anyone have a strategy to catch uniqueness at the EOF level?
Or, is it fine to just rely on the DB throwing an SQLException and
catch
that after ec().saveChanges() ?
(I feel like letting that happen is bad, and might leave EOF in an
un-happy
state - is there any chance of that?)
Thanks again,
-Dan Grec
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--
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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