Automaticly add prefix to rabbitmq message #9292

1 Answer(s)

• 

  0

  enisn created 4 months ago

  Support Team .NET Developer

  Hi,

  I investigated how system works and found the following points.

  The following method is called from everywhere whenever event name required: https://github.com/abpframework/abp/blob/97e10cc7b2b849b0aebf2aa00881616d036b0af1/framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/EventNameAttribute.cs#L22 Since this is a static method, it cannot be overriden in your project.

  Another option seems like overriding RabbitMqDistributedEventBus in your project. Here is the original source code of that class: https://github.com/abpframework/abp/blob/rel-9.1/framework/src/Volo.Abp.EventBus.RabbitMQ/Volo/Abp/EventBus/RabbitMq/RabbitMqDistributedEventBus.cs

  using Microsoft.Extensions.Options;
  using RabbitMQ.Client;
  using Volo.Abp;
  using Volo.Abp.DependencyInjection;
  using Volo.Abp.EventBus;
  using Volo.Abp.EventBus.Distributed;
  using Volo.Abp.EventBus.Local;
  using Volo.Abp.EventBus.RabbitMq;
  using Volo.Abp.Guids;
  using Volo.Abp.MultiTenancy;
  using Volo.Abp.RabbitMQ;
  using Volo.Abp.Timing;
  using Volo.Abp.Tracing;
  using Volo.Abp.Uow;
  
  namespace MyCompanyName.MyApplicationName;
  
  [Dependency(ReplaceServices = true)]
  [ExposeServices(typeof(IDistributedEventBus), typeof(RabbitMqDistributedEventBus), typeof(IRabbitMqDistributedEventBus))]
  public class MyRabbitMqDistributedEventBus : RabbitMqDistributedEventBus
  {
      public MyRabbitMqDistributedEventBus(
          IOptions<AbpRabbitMqEventBusOptions> options,
          IConnectionPool connectionPool,
          IRabbitMqSerializer serializer,
          IServiceScopeFactory serviceScopeFactory,
          IOptions<AbpDistributedEventBusOptions> distributedEventBusOptions,
          IRabbitMqMessageConsumerFactory messageConsumerFactory,
          ICurrentTenant currentTenant,
          IUnitOfWorkManager unitOfWorkManager,
          IGuidGenerator guidGenerator,
          IClock clock,
          IEventHandlerInvoker eventHandlerInvoker,
          ILocalEventBus localEventBus,
          ICorrelationIdProvider correlationIdProvider) : base(options, connectionPool, serializer, serviceScopeFactory, distributedEventBusOptions, messageConsumerFactory, currentTenant, unitOfWorkManager, guidGenerator, clock, eventHandlerInvoker, localEventBus, correlationIdProvider)
      {
      }
  
      public override IDisposable Subscribe(Type eventType, IEventHandlerFactory factory)
      {
          var handlerFactories = GetOrCreateHandlerFactories(eventType);
  
          if (factory.IsInFactories(handlerFactories))
          {
              return NullDisposable.Instance;
          }
  
          handlerFactories.Add(factory);
  
          if (handlerFactories.Count == 1)
          {
              // Here we are registering the consumer for the first time.
              Consumer.BindAsync( "SomePrefix_" + EventNameAttribute.GetNameOrDefault(eventType));
          }
  
          return new EventHandlerFactoryUnregistrar(this, eventType, factory);
      }
  
      protected override Task PublishAsync(IModel channel, string eventName, byte[] body, Dictionary<string, object>? headersArguments = null, Guid? eventId = null, string? correlationId = null)
      {
          eventName += "SomePrefix_" + eventName;
          return base.PublishAsync(channel, eventName, body, headersArguments, eventId, correlationId);
      }
  
      private List<IEventHandlerFactory> GetOrCreateHandlerFactories(Type eventType)
      {
          return HandlerFactories.GetOrAdd(
              eventType,
              type =>
              {
                  var eventName = EventNameAttribute.GetNameOrDefault(type);
                  EventTypes.GetOrAdd(eventName, eventType);
                  return new List<IEventHandlerFactory>();
              }
          );
      }
  }
  

  In that case, you'll override this service both consumer & publisher projects to make consistency.

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