The PipelineBehavior is failing because of a List property in IRequest?

[coderabsolute]

Am getting the following error when I use the PipelineBehavior only when a List is used as a property. Not sure whether the IPipelineBehavior is not handling the List or something am doing incorrectly? When I remove the List property then the code gets executed. Maybe, am doing something wrong, can someone please help me. Thanks in advance!

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.NullReferenceException: Object reference not set to an instance of an object.
   at MediatR.Internal.RequestHandlerWrapperImpl`2.<>c__DisplayClass0_1.<Handle>b__2()
   at MediatR.Internal.RequestHandlerWrapperImpl`2.Handle(IRequest`1 request, CancellationToken cancellationToken, ServiceFactory serviceFactory)
   at MediatR.Mediator.Send[TResponse](IRequest`1 request, CancellationToken cancellationToken)
   at Api.Controllers.CustomersController.Post(CustomerAddRequest model) in \Controllers\CustomersController.cs:line 23
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextExceptionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ExceptionContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIIndexMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Here is the actual code am executing.

public class CustomerAddRequest : IRequest<CommandResponse>
{
	public string CustomerName { get; set; }
	public string CustomerCode { get; set; }
	public string RegistrationNumber { get; set; }
	public string ShortName { get; set; }
	public double CreditLimit { get; set; }
	public IEnumerable<AddressAddRequest> Addresses { get; set; }
}

public class AddressAddRequest
{
	public int AddressTypeId { get; set; }

	public string Address1 { get; set; }
	public string Address2 { get; set; }
	public string Address3 { get; set; }
	public string City { get; set; }
	public string State { get; set; }
	public int CountryId { get; set; }
	public string ZipCode { get; set; }
}


public class CustomerAddPipelineBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
	where TRequest : CustomerAddRequest
	where TResponse : CommandResponse
{
	public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
	{
		return await next();
	}
}

The Addresses property in the AddressAddRequest class is causing the issue. If I remove this property all works well. Any guess please? :)

public IEnumerable<AddressAddRequest> Addresses { get; set; }

This is how am registering with the ServiceCollection.

services.AddScoped(typeof(IPipelineBehavior<,>), typeof(CustomerAddPipelineBehavior<,>));

[coderabsolute]

Looks like the problem is something else, I have a problem registering multiple classes for IPipelineBehavior using ASP.NET DI. I will do a search on google to find out more.

[coderabsolute]

I resolved by passing in the Classes like this. Is there a better way to handle this? If not, I will close this issue.

services.AddScoped(typeof(IPipelineBehavior<CustomerAddRequest, CommandResponse>), typeof(CustomerAddBehavior<CustomerAddRequest, CommandResponse>));
services.AddScoped(typeof(IPipelineBehavior<BrandDeleteRequest, CommandResponse>), typeof(BrandDeleteBehavior<BrandDeleteRequest, CommandResponse>));
services.AddScoped(typeof(IPipelineBehavior<CustomerDeleteRequest, CommandResponse>), typeof(CustomerDeleteBehavior<CustomerDeleteRequest, CommandResponse>));

[jbogard]

What did your original registration look like?

…

On Tue, Oct 2, 2018 at 10:37 PM coderabsolute ***@***.***> wrote: I resolved by passing in the Classes like this. Is there a better way to handle this? If not, I will close this issue. services.AddScoped(typeof(IPipelineBehavior<CustomerAddRequest, CommandResponse>), typeof(CustomerAddBehavior<CustomerAddRequest, CommandResponse>)); services.AddScoped(typeof(IPipelineBehavior<BrandDeleteRequest, CommandResponse>), typeof(BrandDeleteBehavior<BrandDeleteRequest, CommandResponse>)); services.AddScoped(typeof(IPipelineBehavior<CustomerDeleteRequest, CommandResponse>), typeof(CustomerDeleteBehavior<CustomerDeleteRequest, CommandResponse>)); — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#317 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAGYMnSKblrdJ96HOmdYDOOWtjauAsXZks5uhDDwgaJpZM4XD60U> .

[coderabsolute]

These my original registrations which didn't resolve by itself. Maybe, am missing out something?

services.AddScoped(typeof(IPipelineBehavior<,>), typeof(CustomerAddBehavior<,>));
services.AddScoped(typeof(IPipelineBehavior<,>), typeof(BrandDeleteBehavior<,>));
services.AddScoped(typeof(IPipelineBehavior<,>), typeof(CustomerDeleteBehavior<,>));

[jbogard]

Ah. You can't do generic type constraints with vanilla MS.Extensions.DI. See my PR to fix this:

aspnet/DependencyInjection#635

[jbogard]

If you want generic constraints, you have to pull in an 3rd-party container.