如何解决在公共交通中发布事件时,某些消息属性为空 配置事件接口发布
我有一个普通的 .Net Web API 项目,为了学习事件驱动架构,我开始了一个小项目。我是公共交通的新手,我已经使用他们的文档编写了代码。我使用 bus.Send(command) 作为命令,使用 bus.Publish(event) 作为事件。当我发送命令时,我在命令处理程序中收到所有预期值,但在发布某些属性时为空。当我由于某种原因发布消息时,Id 和 EntityThatTookAction 为空,但填充了其他属性。我不明白这种行为的原因。我错过了什么吗?我真的很感激这方面的帮助
配置
services.AddMassTransit(massTransitConfig =>
{
massTransitConfig.AddConsumer<UserEventConsumer>();
massTransitConfig.AddConsumer<UserCommandHandler>();
massTransitConfig.AddConsumer<TodoListEventConsumer>();
massTransitConfig.AddConsumer<TodoListCommandHandler>();
massTransitConfig.UsingRabbitMq((context,rabbitMqConfig) =>
{
rabbitMqConfig.Host(new Uri(busConfig["Url"]),h =>
{
h.Username(busConfig["Username"]);
h.Password(busConfig["Password"]);
});
rabbitMqConfig.ReceiveEndpoint(nameof(UserEventConsumer),cfg =>
{
cfg.PurgeOnStartup = true;
cfg.PrefetchCount = 10;
cfg.Bind<UserCreatedEvent>();
cfg.Bind<UserUpdatedEvent>();
cfg.Bind<UserDeletedEvent>();
cfg.ConfigureConsumer(context,typeof(UserEventConsumer));
});
rabbitMqConfig.ReceiveEndpoint(nameof(UserCommandHandler),cfg =>
{
cfg.PurgeOnStartup = true;
cfg.PrefetchCount = 10;
cfg.Bind<CreateUserCommand>();
cfg.Bind<UpdateUserCommand>();
cfg.Bind<DeleteUserCommand>();
cfg.ConfigureConsumer(context,typeof(UserCommandHandler));
EndpointConvention.Map<CreateUserCommand>(cfg.InputAddress);
EndpointConvention.Map<UpdateUserCommand>(cfg.InputAddress);
EndpointConvention.Map<DeleteUserCommand>(cfg.InputAddress);
});
rabbitMqConfig.ReceiveEndpoint(nameof(TodoListEventConsumer),cfg =>
{
cfg.PurgeOnStartup = true;
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer(context,typeof(TodoListEventConsumer));
});
rabbitMqConfig.ReceiveEndpoint(nameof(TodoListCommandHandler),cfg =>
{
cfg.PurgeOnStartup = true;
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer(context,typeof(TodoListCommandHandler));
EndpointConvention.Map<CreateTodoListCommand>(cfg.InputAddress);
EndpointConvention.Map<UpdateTodoListCommand>(cfg.InputAddress);
EndpointConvention.Map<DeleteTodoListCommand>(cfg.InputAddress);
});
});
});
事件
public class UserCreatedEvent : IBaseEvent
{
public string Id { get; }
public string Message { get; }
public string EntityThatTookAction { get; }
public DateTimeOffset CreatedOn { get; }
public EntityType EntityType { get; }
public Guid CorrelationId { get; }
public UserCreatedEvent(string entityId,string entity,EntityType entityType,Guid correlationId,DateTimeOffset createdOn)
{
Id = entityId;
EntityThatTookAction = entity;
CreatedOn = createdOn;
EntityType = entityType;
CorrelationId = correlationId;
Message = "User list created";
}
}
接口
public interface IBaseEvent : CorrelatedBy<Guid>
{
public string Id { get; }
public string Message { get;}
public string EntityThatTookAction { get;}
public DateTimeOffset CreatedOn { get;}
public EntityType EntityType { get; }
}
发布
var message = new UserCreatedEvent(entityId,entity,EntityType.User,correlationId,DateTimeOffset.UtcNow);
await _bus.Publish(message);
解决方法
您没有发布有效的命令合同,但我会寻找两者之间的任何差异,看看可能会发生什么。可能是您的属性上没有 { get; private set; }
,但我不记得是否需要这样做。我认为它需要可设置才能使反序列化工作。如果您使用的是 .NET 5,则可以指定 { get; init; }
。
另外,我清理了你的总线配置,你很可能不想使用 PurgeOnStartup
,而 EndpointConvention
是 frowned upon。
services.AddMassTransit(massTransitConfig =>
{
massTransitConfig.AddConsumer<UserEventConsumer>();
massTransitConfig.AddConsumer<UserCommandHandler>();
massTransitConfig.AddConsumer<TodoListEventConsumer>();
massTransitConfig.AddConsumer<TodoListCommandHandler>();
massTransitConfig.UsingRabbitMq((context,rabbitMqConfig) =>
{
rabbitMqConfig.Host(new Uri(busConfig["Url"]),h =>
{
h.Username(busConfig["Username"]);
h.Password(busConfig["Password"]);
});
rabbitMqConfig.ReceiveEndpoint(nameof(UserEventConsumer),cfg =>
{
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer<UserEventConsumer>(context);
});
rabbitMqConfig.ReceiveEndpoint(nameof(UserCommandHandler),cfg =>
{
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer<UserCommandHandler>(context);
});
rabbitMqConfig.ReceiveEndpoint(nameof(TodoListEventConsumer),cfg =>
{
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer<TodoListEventConsumer>(context);
});
rabbitMqConfig.ReceiveEndpoint(nameof(TodoListCommandHandler),cfg =>
{
cfg.PrefetchCount = 10;
cfg.ConfigureConsumer<TodoListCommandHandler>(context);
});
});
});
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