[hibernate-issues] [Hibernate-JIRA] Created: (HBX-1110) Support for abstract/concrete pairs of POJO generation for hbm2java

[Jeff Walker (JIRA)]

Support for abstract/concrete pairs of POJO generation for hbm2java
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                 Key: HBX-1110
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HBX-1110
             Project: Hibernate Tools
          Issue Type: Patch
          Components: ant, hbm2java, reverse-engineer
    Affects Versions: 3.2.4 Beta1
         Environment: Hibernate 3.3.1GA, DB2 8.2, ant 1.6.5, Java 5.0 b11, eclipse (myEclipse blue 7.0) on windows xp sp3
            Reporter: Jeff Walker
            Priority: Minor
         Attachments: HibernateExt.patch

I wanted hbm2java to be able to produce pairs of both abstract base classes and concrete classes for each POJO when reverse engineering.

I altered the ant tasks to allow this syntax:
<hbm2java ejb3="true" jdk5="true">
    <base transform="{package-name}/base/{class-name}Base"/>
    <concrete transform="{package-name}/{class-name}"/>
</hbm2java> 

I then extended the POJO exporter (used only when base or concrete are present).  This new exporter takes the meta model and runs once for all components, and then twice for each entity.  The first entity run is for the base classes.  Using the meta property overrides in the exporter, I force the class to be abstract, and change the generated class name according to the "transform" attribute.  I also save the name of the generated class name in a hash, mapped to the original name for use in the second phase.

Then for the second run (still inside of the exporter), I force the generated class name (again via the "transform" attribute), and have the class extend the base class that was generated in the first phase.

I also introduce two new variables into the template context: basePartOfPair and concretePartOfPair.  Set to true or false for the respective phase.  They default to false for when the regular exporter is used.

In the templates I forced the properties to be protected (instead of private), and turned off the property generation for the concrete class.  I have code in the method (exportPersistentClass) to override these at meta properties, but that didn't work, as those properties need to be set on the property level, not the class level.

You may refer to the following forum post for more background: http://forum.hibernate.org/viewtopic.php?t=994243

Note that there is no test case for this functionality yet.  I'm not sure where to put it or what to do with that, but I will keep looking at that.

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