I have a lot of persistent classes. They all descend from a particular base class in my java that has some core fields that I want every object to have e.g.

createdOn
createdBy
lastUpdateOn
lastUpdateBy

For my java, it's a no brainer. If I add a new class "foo" and I subclass "parent", it gets those four fields automatically by virtue of the class inheritance.

When I go to map foo in my .hbm.xml file though, I end up having to map those four fields manually. The problem gets more annoying when, like this morning, we add a new "universal" field and I have to go out and write a script to update like 100 .hbm files to add the new field.

Is there any way (short of the performance killer of making *everything* a joined subclass), to tell hibernate that I want *everything* I map to derive from or otherwise contain a specific set of fields?

<property name="metaInfo" type="myCustomUserTypeThatKnowsHowToMap4Fields"/>

Can you point me to somewhere in the doc that discusses how to do this? Neither my copy of Hibernate in action, nor the online doc seem to offer much in the way of insight.

Section 6.2.3 of the 3.0.5 docs

There is half a chapter about UserTypes in HiA...

I hit the submit button a little quick...

I would also recommend looking at the org.hibernate.test package. You can do a search for UserType and find several examples.

Yah, I found that, but I wasn't sure if that's the implementation you were pointing to because I don't think it's going to work for me.

As I understand it, if I go down the custom type road, I'll end up with an object foo which contains a customer type metaInfo. I can then reference the meta fields via

foo.metaInfo.createdOn

Right now though, I have lots of code in existence which relies on being able to do

foo.createdOn

So by going to a custom type I'm changing the access path, am I not?

Likewise, can I even use a custom type if I want to universally map a collection as part of the type? This whole thing started this morning when we decided to add an attachments set to each and every class in the model. So my metadata atm contains:

createdOn -- timestamp
createdBy -- user
lastUpdatedOn -- timestamp
lastUpdatedBy - user
attachments -- <set>

Looking through the custom type API it seems like I can whip up a metaInfo for the first four e.g.

public String[] getPropertyNames() {
return new String[] {"lastUpdatedOn", "lastUpdatedBy", "createdOn", "createdBy"}
}


public String[] getPropertyNames() {
return new String[] {Hibernate.TIMESTAMP, ?Hibernate.CLASS?, Hibernate.TIMESTAMP, ?Hibernate.CLASS?,}
}

How do I map a *set* though? There is no Hibernate.SET, and there's the additional issue that you need a lot more information to define a set than a scalar.

Use delegate methods. Eclipse will even write them for you if you're using that.



Add in null protection, etc. as appropriate.

<Bonk> Yah, that'll solve the access path concern. Any idea if there exists a way to put a set in a User Type though (the second concern I had)?