Kumuluzee JPA Persistence settings outside persistence unit

Question

We are trying to configure the Kumuluz JPA.

We would like to tailor the Persistence Unit programmatically and for that, we need a handle on the PersistenceUnit Properties. This is already pre-packaged inside the kumuluz jpa dependency and we have apparently no way of getting a handle on the properties at runtime.

Has anyone had the same problem of having to set the properties at runtime? Can you please share your methods?

Answer 1

You cannot access persistence.xml configuration in runtime, nor would it make any sense to do so, since persistence.xml is read by JPA provider only at the very beginning of the application start-up.

You can, however, configure persistence.xml during build time with maven configuration, by using Maven Resources Plugin. For example:

pom.xml:

<project>
  ...
  <properties>
    <db.action>create</db.action>
  </properties>
  ...
  <build>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
      </resource>
    </resources>
  </build>
  ...
</project>

persistence.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
             http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
             version="2.1">
    <persistence-unit name="kumuluzee-samples-jpa" transaction-type="JTA">

        <jta-data-source>jdbc/CustomersDS</jta-data-source>

        <class>com.kumuluz.ee.samples.jpa.Customer</class>

        <properties>
            <property name="javax.persistence.schema-generation.database.action" value="${db.action}"/>
        </properties>
    </persistence-unit>
</persistence>