Why Are RepositoryEventHandler Methods Not Being Invoked in Spring Data Rest?

Why are the methods of RepositoryEventHandler not being invoked in my Spring Data Rest application?

@Component
public class MyEventHandler {
    @HandleAfterCreate
    public void handleAfterCreate(Object entity) {
        // logic after entity creation
    }
}

In Spring Data REST, the `RepositoryEventHandler` allows you to listen for domain events associated with repositories. If these methods are not being invoked, it could be due to several configuration or implementation issues that prevent your event listeners from triggering.

@EnableSpringDataWebSupport
@Configuration
public class SpringDataConfig {
    @Bean
    public RepositoryRestConfigurer repositoryRestConfigurer() {
        return new RepositoryRestConfigurer() {
            @Override
            public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
                config.setBasePath("/api");
            }
        };
    }
}

Causes

• The event handler is not registered as a Spring bean.
• The event type being observed does not match the event handler method's annotation.
• The Spring Data REST is not properly configured to scan or recognize the event handler classes.

Solutions

• Ensure your event handler class is annotated with `@Component` or similar to register as a Spring bean.
• Verify that the event method annotations (`@HandleAfterCreate`, etc.) match the events you expect to handle.
• Check your Spring configuration for enabling Spring Data REST to properly use event handlers.

Mistake: Assuming the event handler is automatically detected without requiring a proper registration.

Solution: Use `@Component` annotation or provide configuration to explicitly declare the component.

Mistake: Incorrectly defining method parameters in event handler methods; they must match the entity type.

Solution: Ensure method signatures match the types of the events you are handling.