Tapestry5, JPA 2 and Hibernate

The documentation for Integrating JPA found on the Tapestry5 website was lacking.

1. It doesn't tell you that you have add the Tapestry-jpa dependency in you project POM
2. It uses EclipseLink
3. Explicitly tell you to use JPA 2.0 NOT JPA 2.1;

So, I had a few problems to fix after reading and following the docs. With much tinkering with my Tapestry5 (5.4-beta-35) project, I figured out:

1. To add the Tapestry-jpa dependency
   <dependency> <groupId>org.apache.tapestry</groupId> <artifactId>tapestry-jpa</artifactId> <version>5.4-beta-35</version> </dependency>
    
   
2. Hibernate 4.2 instead of EclipseLink
   <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>4.2.20.Final</version> </dependency>
   
3. Edit the persistence.xml header so it reads version=2.0 instead of 2.1. This is because my Netbeans IDE can generate the persistence.xml file but defaults to 2.1 version instead of 2.0.
   

And if you get a javax.persistence.PersistenceException: Unable to build EntityManagerFactory error during the build, you probably didn't add a hibernate.dialect property in your persistence.xml configs.

Tapestry5, JPA, Netbeans and a FilerException

Tapestry5.4 supports JPA out of the box which is nice. Also Netbeans supports JPA, doubly nice. Now if you're using 2 or more Persistence Units, you have probably encountered a FilerException when you try to compile or run your project. This shouldn't be a problem if you're using only single Persistence Unit. I suspect the fix would be the same if you encounter the same exception.

java.lang.RuntimeException: javax.annotation.processing.FilerException: Attempt to recreate a file for type {myclass}

The {myclass} here is always an entity class.

I think, a secondary symptom of this is if all your entity classes are all in a single package. This should be the case if you're doing a standard Tapestry5 web application.

The fix to this is to edit the Persistence Unit and add a  property and explicitly declare the entity classes on the Persistence Unit.

<persistence-unit name="PayrollPU" transaction-type="RESOURCE_LOCAL">  
   <provider>org.hibernate.ejb.HibernatePersistence</provider>  
   <class>cu.ictso.miscapps.entities.Departments</class>  
   <class>cu.ictso.miscapps.entities.Employee</class>  
   <class>cu.ictso.miscapps.entities.Groups</class>  
   <class>cu.ictso.miscapps.entities.ViewAttendance</class>  
   <exclude-unlisted-classes>true</exclude-unlisted-classes>  
   <properties>  
    <property name="javax.persistence.jdbc.url" value="jdbc:sqlserver://localhost;databaseName=DTR-Payroll2;Integrated Security=false"/>  
    <property name="javax.persistence.jdbc.user" value="PayMaster"/>  
    <property name="javax.persistence.jdbc.driver" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/>  
    <property name="javax.persistence.jdbc.password" value="123456"/>  
    <property name="javax.persistence.schema-generation.database.action" value="create"/>  
   </properties>  
 </persistence-unit>  

Here's an example Persistence Unit.