[hibernate-dev] Modeling natural-id on entity in XML

[Hardy Ferentschik]

On 18 Jan 2014, at 08:32, Steve Ebersole <steve at hibernate.org> wrote:

> As we move to 5.0 and the new unified XML format I'd like to revisit the
> ways we have mapped certain things historically in hbm.xml and improve upon
> them when possible.  At the moment I am looking at mapping of natural ids.
> In hbm.xml the form was to wrap the attributes making up the natural id in
> a grouping:
> 
> <class name="Person">
>    <id name="id"/>
> 
>    <natural-id>
>        <property name="lastName"/>
>        <property name="firstName"/>
>    </natural-id>
> 
>    ...
> </class>

in the context of adding cache config aspects I think I prefer this version.
It groups the properties and more importantly allows to specify the mutability and
cache settings on the enclosing node:

<class name="Person">
   <id name="id"/>

   <natural-id mutable="true|false" cache-region="ABC">
       <property name="lastName"/>
       <property name="firstName"/>
   </natural-id>

   ...
</class>

This is imo more intuitive then:

...
   <natural-id mutable="true|false" cache-region="ABC" />

   <basic name="lastName" natural-id="true" />
   <basic name="firstName" natural-id="true" />
...

> which can become unwieldy if you want these values to exist in other
> groupings.

Are there many potential other groups? If it is a rare case, why not just letting 
the user repeat the properties per group?


—Hardy