Axon5: Spring bean initialization order issue

Axon Framework
1

Hi,

This is a minimal reproducer for a Spring bean initialization issue I hit while migrating from Axon Framework 4 (AF4) to Axon Framework 5 (AF5).

When using a Spring bean that has a QueryGateway injected like this:

@Service
public class SettingsService {
  private final QueryGateway queryGateway;

  public SettingsService(QueryGateway queryGateway) {
    this.queryGateway = queryGateway;
  }
  // some code
}

If we use this bean somewhere else, e.g., in the @Configuration class of a projection:

@Configuration
public class ProjectionConfiguration {

  public static String PROCESSOR_NAME = "courses-processor";


  @Bean
  EventProcessorDefinition coursesProcessor(SettingsService settingsService) {
    return EventProcessorDefinition
        .pooledStreaming(PROCESSOR_NAME)
        .assigningHandlers(descriptor -> descriptor.beanType().getPackageName()
            .endsWith("coursestats.projection"))
        .customized(config -> config
            .initialSegmentCount(4)
            .batchSize(10)
        );
  }
}

and there is an event handling method in that package:

@Component
class SimpleProjector {

  @EventHandler
  void handle(Object event, QueryUpdateEmitter emitter) {
  // empty for demo purposes
  }
}

we get a startup error:

Parameter 0 of constructor in org.axonframework.examples.university.projection.SettingsService required a bean of type 'org.axonframework.messaging.queryhandling.gateway.QueryGateway' that could not be found.

In our existing AF4 apps this pattern worked fine.

Suspected cause: it seems that Axon creates the EventProcessorDefinition beans very early, and at that point the QueryGateway is not yet available for constructor injection in SettingsService.

Question: do we really need to rework the Spring bean dependencies across all our apps, or is there a recommended way to handle this in AF5?

Klaus