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EventBus Shared Across App Services #24


0
daniel created

Following the documentation I've injected the EventBus into both my AppServices, but the events are only being triggered in one app service at a time. Never both. If I remove the EventBus from the first App Service, all the events in the second app service will be triggered.

Is this a bug or have I missed something?

Example code:

public class CommentAppService : ApplicationService, ICommentAppService
	{

		private readonly ICommentRepository _commentRepository;

		public IEventBus EventBus { get; set; }

		public CommentAppService(ICommentRepository commentRepository)
		{
			_commentRepository = commentRepository;

			EventBus = NullEventBus.Instance;
		}

		public Comment CreateCommentForTask(CreateCommentInput input) {
			var comment = new Comment
			{
				CommentText = input.CommentText,
				TaskId = input.TaskId,
				UserId = input.UserId
			};

			EventBus.Trigger(new TaskCommentCreatedEventData(input.TaskId.Value));

			return _commentRepository.Insert(comment);
		}
	}
public class TaskAppService : ApplicationService, ITaskAppService
	{
		private readonly IRepository<Task> _taskRepository;
		
		public IEventBus EventBus;

		public ProjectTaskActionAppService(IRepository<Task> taskRepository
		{
			_taskRepository = taskRepository;

			EventBus = NullEventBus.Instance;
		}

		public void UpdateProjectTaskActionStatus(UpdateTaskStatusInput input)
		{
			var task = _taskRepository.Get(input.TaskId);
			task.Completed = input.Completed

			if(input.Completed)
			{
				// TODO: This isn't being triggered!
				EventBus.Trigger(new TaskCompleteEventData(task.Id));
			}
		}
	}
public class ActivityLogWriter :
		IEventHandler<TaskCommentCreatedEventData>,
		IEventHandler<TaskCompleteEventData>,
		ITransientDependency
	{
		private readonly IRepository<ActivityLog> _activityLogRepository;
		private readonly IRepository<Task> _taskRepository;

		public ActivityLogWriter(
			IRepository<ActivityLog> activityLogRepository,
			IRepository<ProjectTask> taskRepository
			)
		{
			_activityLogRepository = activityLogRepository;
			_taskRepository = taskRepository;
		}

		/// <summary>
		/// Log the event when users comment on a task
		/// </summary>
		/// <param name="eventData"></param>
		public void HandleEvent(TaskCommentCreatedEventData eventData)
		{
			WriteActivity("{User} commented on the task {Task}", null, eventData.TaskId);
		}

		/// <summary>
		/// Store a log when a user completes a task
		/// </summary>
		/// <param name="eventData"></param>
		public void HandleEvent(TaskCompleteEventData eventData)
		{
			WriteActivity("{User} complete the the task {Task}", eventData.TaskId);
		}

		/// <summary>
		/// Writes a log to the system
		/// </summary>
		/// <param name="message">The message to write as a long</param>
		/// <param name="projectTaskId">The project task which the event related to.</param>
		public void WriteActivity(string message, taskId)
		{
			_activityLogRepository.Insert(new ActivityLog
			{
				Message = message,
				TaskId = taskId
			});
		}
	}

1 Answer(s)
  • 0
    hikalkan created
    Support Team

    Hi,

    In the second application service (TaskAppService), EventBus defined wrongly. It should be like:

    public IEventBus EventBus { get; set; }

    NOT like:

    public IEventBus EventBus;

    If you define it as above, Dependency Injection can not set it, and it remains NullEventBus.Instance.