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preUpdateWithChanges [message #515972]

Mon, 22 February 2010 10:54

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

I've got master-detail relationship mapped on both sides; the parent has a list of children, the child a single reference to the parent. When a new child is added, it is added to the parent's list, but in the "real" (database) world there naturally is only a foreign key from the child to the parent.

When persisting this, the preUpdateWithChanges event is fired on the parent. This confuses me, there is nothing to update on the parent.

And Eclipselink actually does not update anything if left alone, but I use this event to set a "who'd done it" field, which results in there being something to update, and I get an update just setting the who and version field. And as a consequence I get a lot of history records containing only a changed who'd-done-it field.

Why is the preUpdateWithChanges event fired when in fact there isn't anything to write to the database?

Tom

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Re: preUpdateWithChanges [message #516601 is a reply to message #515972]

Wed, 24 February 2010 14:26

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

Can anyone shed a light on why the preUpdateWithChanges event fires when the entity has no changes to write to the database? Is this correct?

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Re: preUpdateWithChanges [message #518019 is a reply to message #515972]

Tue, 02 March 2010 19:03

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

The event is fired, because, as you said, there are changes at the object level.

The event object will have an ObjectChangeSet associated with it, you could check this change set to see if the only change was a OneToMany.

You could also use the aboutToUpdate event, it is only fired if the database will be updated.

James : Wiki : Book : Blog : Twitter

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Re: preUpdateWithChanges [message #518033 is a reply to message #518019]

Tue, 02 March 2010 20:02

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

> You could also use the aboutToUpdate event, it is only fired if the
> database will be updated.

Will changes being made in the aboutToUpdate handler still be included?

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Re: preUpdateWithChanges [message #518038 is a reply to message #515972]

Tue, 02 March 2010 20:22

James Sutherland

Messages: 1939
Registered: July 2009
Location: Ottawa, Canada

Senior Member

As long as you make the changes using the event object, they will be applied. (event.updateAttributeWithObject()).

James : Wiki : Book : Blog : Twitter

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Re: preUpdateWithChanges [message #518047 is a reply to message #518038]

Tue, 02 March 2010 20:40

Tom Eugelink

Messages: 817
Registered: July 2009

Senior Member

> As long as you make the changes using the event object, they will be
> applied. (event.updateAttributeWithObject()).

Ok. I'm going to try this other approach I started today first; I know which properties are "changing" properties and which ones are not, so I should be able to set a boolean myself.

Tom

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