I am working on a project where we are using the *.hbm.xml as the basis for both generating the classes and the schema and we have hit a point where we really want to add behavior to the generated (persistent) classes.

Is there a best practice for this that either allows us to save modifications to the generated classes or to somehow use one class mapping at class generation time and another (the subclass with added behavior) at run time?

Since we have not yet solidified the object model, we don't want to blindly edit the generated classes.

Alternately, should we dump the *.hbm.xml-centric approach and move to generating that file from the java class?

Thanks

Ted,

You can specify a base class to generate, which you can then extend and add your business logic to. All hibernate access is then done through your base class.

Take a look at this page for more info: http://www.onjava.com/pub/a/onjava/2005 ... ntent=text

For your convenience I've c+p'd the important bits here:

Using a Base Class
You can also use the generated-class meta attribute to define a base class, which will be generated by hbm2java, leaving you free to place your business logic in a subclass of this generated class. For example, using this technique for the Country class could be done as follows:


<class name="Country" table="COUNTRY" dynamic-update="true">
<meta attribute="implement-equals">true</meta>
<meta attribute="generated-class">CountryBase</meta>
<meta attribute="scope-field">protected</meta>

<id name="id" type="long" unsaved-value="null" >
<column name="cn_id" not-null="true"/>
<generator class="increment"/>
</id>

<property column="cn_code" name="code" type="string"/>
<property column="cn_name" name="name" type="string"/>

<set name="airports" >
<key column="cn_id"/>
<one-to-many class="Airport"/>
</set>
</class>

hbm2java will generate the CountryBase class, containing all the attributes, getters, setters, etc. described by the mapping file. Then you are free to place your business logic in the derived class called Country, which will be used and instantiated by Hibernate; for example:


public class Country extends CountryBase {
/**
* Add an airport to this country
*/
public void addAirport(Airport airport) {
airport.setCountry(this);
if (getAirports() == null) {
setAirports(new java.util.HashSet());
}
getAirports().add(airport);
}
}