Filter

Subscriber filters are similar to ASP.NET MVC filters and are mainly used to perform additional work before and after the subscriber method executes, such as transaction management or logging.

Creating a Subscriber Filter

Create Filter

Create a new filter class that inherits from the SubscribeFilter abstract class.

public class MyCapFilter : SubscribeFilter
{
    public override Task OnSubscribeExecutingAsync(ExecutingContext context)
    {
        // Execute before the subscriber method runs
    }

    public override Task OnSubscribeExecutedAsync(ExecutedContext context)
    {
        // Execute after the subscriber method completes
    }

    public override Task OnSubscribeExceptionAsync(ExceptionContext context)
    {
        // Handle exceptions during subscriber method execution
    }
}

In some scenarios, if you want to terminate the subscriber method execution, you can throw an exception in OnSubscribeExecutingAsync, and choose to handle the exception in OnSubscribeExceptionAsync.

To ignore exceptions, set context.ExceptionHandled = true in ExceptionContext:

public override Task OnSubscribeExceptionAsync(ExceptionContext context)
{
    context.ExceptionHandled = true;
}

Registering a Filter

Use AddSubscribeFilter<> to register a filter.

services.AddCap(opt =>
{
    // ...
}).AddSubscribeFilter<MyCapFilter>();

Currently, multiple filters are not supported.