Skip to main content
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [dali-dev] Entity property listener
Title: Entity property listener
Hey, Paul,
 
I got it - listener1 solves my issue!
 
Best wishes!
Stefan Dimov

From: dali-dev-bounces@xxxxxxxxxxx [mailto:dali-dev-bounces@xxxxxxxxxxx] On Behalf Of Dimov, Stefan
Sent: Thursday, June 25, 2009 3:21 PM
To: General Dali EJB ORM developer discussion.
Subject: [LIKELY JUNK]RE: [LIKELY JUNK]Re: [dali-dev] Entity property listener

Hey Paul,
 
10x 4 the info. It helped. But not entirely. Now I have another issue.
 
Let's say that I have an attribute annotated with  @OneToOne. If I add to this annotation (mappedBy="someAttr"), which is the listener and where I have to add it in order to catch that change? The listener2 you describe below doesn't work, because the joining strategy of the relationship reference of the corresponding attribute is null and I can't add a reference to it.
 
Best wishes!
Stefan Dimov
From: dali-dev-bounces@xxxxxxxxxxx [mailto:dali-dev-bounces@xxxxxxxxxxx] On Behalf Of Paul Fullbright
Sent: Tuesday, June 23, 2009 6:13 PM
To: General Dali EJB ORM developer discussion.
Subject: [LIKELY JUNK]Re: [dali-dev] Entity property listener

Hey Stefan,

This area has seen significant churn this past release in order to support extensibility, but it has also improved some UI functionality as well.

A RelationshipMapping now has a RelationshipReference that describes how the two entities involved are joined across the relationship.  A RelationshipReference has a predominant joining strategy that may, among other things, be a join table, join columns, or it may specify the joining to be controlled by the other side of the relationship (mappedBy).  When it is mapped by the other side of the relationship, the predominant joining strategy is a MappedByJoiningStrategy and that joining strategy has the property MAPPED_BY_ATTRIBUTE_PROPERTY that you are used to looking for on the mapping itself.

In other words, you may do the following:

((RelationshipMapping) JavaPersistentAttribute.getMapping()).getRelationshipReference().addPropertyChangeListener(RelationshipReference.PREDOMINANT_JOINING_STRATEGY_PROPERTY, listener1);

where listener1 is listening for changes to the joining strategy.  That is, this property change will signal whether the mapping is now using a join table rather than join columns, for instance, but will not give change notification to the inner workings of the joining strategy.  ((As an aside, I'd recommend using a targeted listener (using the property name while adding the change listener) instead of the anonymous method you chose.  The name of the property (or list or collection) gives clues as to what type of change event it is, and the interface where it is located tells you on which object to register the listener.))  At any rate, once you know you have a MappedByJoiningStrategy you may then do:

MappedByJoiningStrategy.addPropertyChangeListener(MappedByJoiningStrategy.MAPPED_BY_ATTRIBUTE_PROPERTY, listener2);

where listener2 is listening for changes in the actual attribute.

Hope this helps,
- Paul
-- 
Paul Fullbright
Eclipse Java Persistence Tools (Dali) Development
Oracle

Dimov, Stefan wrote:

Hi, all,

In SAP NWDS I'm working on a tool which needs to know if the 'mappedBy' attribute of the annotation of the owned side of a bi-directional relation has been changed. In order to do that, I'm adding a listener to the owned side relation attribute by using:

JavaPersistentAttribute.getMapping().addPropertyChangeListener(lsnr)

But the specified listener doesn't get any events when I change the mappedBy attribute in the java code.

It was working in the old DALI, but now when we adopted our NWDS to the new DALI it's not working anymore.

Am I using the wrong kind of listener or do I have to open a bug in the bugzilla?


Best wishes!
Stefan Dimov 


_______________________________________________
dali-dev mailing list
dali-dev@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/dali-dev

Back to the top