WILDFLY/JBOSS: WFLYJPA0061: Persistence unitName was not specified and multiple persistence unit definitions

  

>PROBLEM

Creating a persistence.xml file having two persistence units caused the following Wildfly's error message:

Caused by: java.lang.IllegalArgumentException: WFLYJPA0061: Persistence unitName was not specified and there are 2 persistence unit definitions in application deployment deployment "todos.war". Either change the application deployment to have only one persistence unit definition or specify the unitName for each reference to a persistence unit.

The persistence.xml configuration used was:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
   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">
        
    <persistence-unit name="primary">
       <jta-data-source>java:jboss/datasources/TasksJsfQuickstartDS</jta-data-source>
       <properties>
          <!-- Properties for Hibernate -->
          <property name="hibernate.hbm2ddl.auto" value="create-drop" />
          <property name="hibernate.show_sql" value="false" />
       </properties>
    </persistence-unit>

    <persistence-unit name="pgTestoneDS">
       <jta-data-source>java:jboss/datasources/pgTestoneDS</jta-data-source>
       <properties>
<!--           <property name="hibernate.hbm2ddl.auto" value="create-drop" /> -->
<!--           <property name="hibernate.show_sql" value="false" /> -->
       </properties>
    </persistence-unit>

</persistence>

 

>SOLUTION

After some failures, I've decided to repeat the same configuration but doing the things in a different order.
The following order was successful:

1. Refactor the code that concerns the primary persistent-unit (or the the initial persistent-unit, whatever the name it has).

2. Create a qualifier to this first perstent-unit.

3. Refactor the dao layer in order to apply the its qualifier where the entity maneger is injected.

4. Recompile the project and perfome a full deploy.

5. Start the server and test.

6. Stop the server

7. If not successful, fix the code revising from step 1.

8. if successful, add the second persistent-unit to persistence.xml file.

9. Create the  database manager class, its qualifier, the entities and dao layer always using the respective qualifier for the second persistent-unit to differ from the initial code implemented for the first persistent-unit.

10. Recompile the project and perfome a full deploy.

11. Start the server and test.

Source code available at the link below.

>WHAT NOT TO DO

This site is dedicated to provide straight problem/solution approach, but sometimes it is valuable to lean from the mistakes but this kind of approach doesn't fit here.
To get more details and source code, point to WILDFLY/JBOSS: WFLYJPA0061: Persistence unitName was not specified and double persistence unit definitions

>ENV

Windows 10
Wildfly 18
JEE/CDI/JPA