How to I register FluentValidation validators in external assemblies when using Nancy and .Net Core?

[dimitridaras]

Description

I am using Nancy.Validation.FluentValidation (v2.0.0--clinteastwood), but I am unable to register IValidator classes in my DI container (I am using Autofac), apparently because they are in an external assembly.

According to the documentation, you used to have to call AppDomainAssemblyTypeScanner.LoadAssemblies to explicitly scan those assemblies, but this class no longer exists. How should validators now be registered?

I am using NancyFX v2.0.0-clinteastwood and .Net Core v2.1. See https://stackoverflow.com/q/52655150/42119

Steps to Reproduce

• Reference Nancy.Validation.FluentValidation v2.0.0--clinteastwood in your Nancy project.
• Reference another project that contains classes inheriting AbstractValidator<T>
• Ensure that the validator is loaded in the DI tree
• The DI container will throw an error on startup. With Autofac, the error is: Cannot resolve parameter 'FluentValidation.IValidator

System Configuration

.Net Core v2.1 OSX 10.13.6

• Nancy version: v2.0.0-clinteastwood
• Nancy host
  • [ ] Nancy.Owin
• Other Nancy packages and versions:
  • [ ] Nancy.Validation.FluentValidation v2.0.0--clinteastwood
• Environment (Operating system, version and so on): OSX 10.13.6
• .NET Framework version: .Net Core v2.1

[dimitridaras]

My error. It appears that I have to be more specific with my DI registrations for the validator than I had to be with Web Api. I have to register the specific validators such as

builder.RegisterType<MyTypeValidator>().As<IValidator<MyType>>();

whereas with Web Api I didn't have to be so specific. I am using the decorator pattern, and with Autofac I could register the decorator via

builder.RegisterType<MyTypeHandler>()
                                .Named<IHandler<MyType, IEnumerable<ReturnType>>>("handler");

containerBuilder.RegisterGenericDecorator(typeof(ValidationDecorator<,>),
                                                      typeof(MyTypeHandler<,>),
                                                      fromKey: "handler");