Changing Persistence Unit dynamically - JPA

Question

Persistence units in persistence.xml are created during building the application. As I want to change the database url at runtime, is there any way to modify the persistence

Answer 1

If you are using Thorntail framework, you can wire-up the persistence.xml file to fetch runtime variables from "project-defaults.yml" file.

    org.hibernate.ejb.HibernatePersistence
    com.package.jpa.EntityClass1
    com.package.jpa.EntityClass2
    com.package.jpa.EntityClass3
    
        
        
        


        
        
        


        
        
    

Take note of the dynamic DB values in ${...} as the point to values in the project-default.yml file.

Then you project-defaults.yml file will have an entry like this:

    thorntail:
       http:
         port: 8989
       datasources:
          data-sources:
             my-postgres-ds:
                driver-name: my-postgres-driver
                connection-url: "jdbc:postgresql://localhost:5432/my-db-name"
                user-name: my-user-name
                password: "my-password#"
          jdbc-drivers:
             my-postgres-driver:
                driver-module-name: org.postgresql
                driver-xa-datasource-class-name: org.postgresql.xa.PGXADataSource

I expect this should also work for Spring boot using application.properties and persistence.xml