4.8.3. Extending Business Logic

The main part of platform business logic is contained in Spring beans. This enables to easily extend or override it in the application.

To substitute a bean implementation, you should create your own class that implements the interface or extends the base platform class and register it in spring.xml of the application. You cannot apply the @Component annotation to the extending class; overriding beans is possible only in the XML configuration.

Below is an example of adding a method to the PersistenceTools bean.

First, create a class with the necessary method:

public class ExtPersistenceTools extends PersistenceTools {

  public Entity reloadInSeparateTransaction(final Entity entity, final String... viewNames) {
      Entity result = persistence.createTransaction().execute(new Transaction.Callable<Entity>() {
          @Override
          public Entity call(EntityManager em) {
              return em.reload(entity, viewNames);
          }
      });
      return result;
  }
}

Register the class in spring.xml of the project core module with the same identifier as the platform bean:

<bean id="cuba_PersistenceTools" class="com.sample.sales.core.ExtPersistenceTools"/>

After that, the Spring context will always return ExtPersistenceTools instead of the base`PersistenceTools` instance. A checking code example:

Persistence persistence;
PersistenceTools tools;

persistence = AppBeans.get(Persistence.class);
tools = persistence.getTools();
assertTrue(tools instanceof ExtPersistenceTools);

tools = AppBeans.get(PersistenceTools.class);
assertTrue(tools instanceof ExtPersistenceTools);

tools = AppBeans.get(PersistenceTools.NAME);
assertTrue(tools instanceof ExtPersistenceTools);