Axon框架：如何在domain_event_entry表中回滚

Question

您可以在下面看到我的示例类。

基本上，我希望使用Axon的domain_event_entry表来存储事件，并使用我自己的实体表来存储实体。我知道，如果我激发在聚合中处理的createTemplateCommand，将发布一个事件，之后它将转到@eventsourcinghandler，Axon将在其domain_event_entry表中持久化该事件。

如何回滚domain_event_entry表，还是应该为此使用补偿事件？

@Aggregate
@Getter
@Setter
@NoArgsConstructor
public class TemplateAggregate {

  private static final transient Logger logger = LoggerFactory.getLogger(TemplateAggregate.class);
  @AggregateIdentifier
  private String templateId;

   private LocalDate createdAt;

   private String createdBy;

   private String description;

   private LocalDate modifiedAt;

   private String modifiedBy;

   private String name;

   private LocalDate validFrom;

   private LocalDate validTo;

   private File file;

   private String fileName;

   private long fileSize;

   private LocalDate fileDate;

   private String fileUploader;

  @CommandHandler
  public TemplateAggregate(CreateTemplateCommand cmd) {
    AggregateLifecycle.apply(new TemplateCreatedEvent(cmd));
  }

  @CommandHandler
  public void handle(ModifyTemplateCommand cmd) {
    AggregateLifecycle.apply(new TemplateModifiedEvent(cmd));
  }

  @EventSourcingHandler
  public void on(TemplateCreatedEvent event) {
    this.templateId = event.getTemplateId();
     this.createdAt = event.getCreatedAt();
     this.createdBy = event.getCreatedBy();
     this.description = event.getDescription();
     this.name = event.getName();
     this.validFrom = event.getValidFrom();
     this.validTo = event.getValidTo();
     this.file = event.getFile();
     this.fileName = event.getFileName();
     this.fileSize = event.getFileSize();
     this.fileDate = event.getFileDate();
     this.fileUploader = event.getFileUploader();
    logger.info("TemplateAggregate - TemplateCreatedEvent");
  }

  @EventSourcingHandler
  public void on(TemplateModifiedEvent event) {
    this.templateId = event.getTemplateId();
     this.createdAt = event.getCreatedAt();
     this.createdBy = event.getCreatedBy();
     this.description = event.getDescription();
     this.name = event.getName();
     this.validFrom = event.getValidFrom();
     this.validTo = event.getValidTo();
     this.file = event.getFile();
     this.fileName = event.getFileName();
     this.fileSize = event.getFileSize();
     this.fileDate = event.getFileDate();
     this.fileUploader = event.getFileUploader();
     this.modifiedAt = event.getModifiedAt();
     this.modifiedBy = event.getModifiedBy();
    logger.info("TemplateAggregate - TemplateModifiedEvent");
  }

}

我的外部@EventHandler类：

@Service
public class TemplateCreatedEventHandler {

  private static final transient Logger logger =
      LoggerFactory.getLogger(TemplateCreatedEventHandler.class);

  @Autowired
  private TemplateRepository templateRepository;

  @Transactional
  @EventHandler
  public void on(TemplateCreatedEvent event) {
    templateRepository.save(new TemplateQueryEntity(event));
    logger.info("EventHandler - TemplateCreatedEvent");
    throw new RuntimeException();
  }



}

Answer 1

这是跟踪事件处理器的正确和预期行为。事件存储是真理的来源，一旦您的TemplateCreatedEvent在事件存储中持久化，这意味着“模板创建的事件已经发生”。

您的事件处理器无法处理该事件，并引发和异常。这意味着TemplateCreatedEventHandler中的事务将回滚。这并不意味着历史突然被改变；您的事件处理程序不能决定TemplateCreatedEvent没有发生。

当您稍后为TemplateCreatedEventHandler推出一个修复程序以便它能够处理该事件（移除RuntimeException）时，处理程序将处理该事件并持久化该实体。

https://docs.axoniq.io/reference-guide/configuring-infrastructure-components/event-processings/event-processors#处理期间的异常