System.AggregateException: Some services are not able to be constructed (Error while validating the service ..'ServiceType: MediatR.IRequestHandler - asp.net-web-api

Question

My CQRS file layout is as in the picture. Whenever I enable the handler inside the GetAllBooks folder, I get an error.
Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: MediatR.IRequestHandler2[BookAPI.Application.Features.Queries.Book.GetAllBooks.GetAllBookQueryRequest,System.Collections.Generic.List1[BookAPI.Application.Features.Queries.Book.GetAllBooks.GetAllBookQueryResponse]] Lifetime: Transient ImplementationType: BookAPI.Application.Features.Queries.Book.GetAllBooks.GetAllBookQueryHandler': Unable to resolve service for type 'BookAPI.Application.Repositories.IBookReadRepository' while attempting to activate 'BookAPI.Application.Features.Queries.Book.GetAllBooks.GetAllBookQueryHandler'.)
GetAllBookQueryHandler
public class GetAllBookQueryHandler : IRequestHandler<GetAllBookQueryRequest, List<GetAllBookQueryResponse>>
{
private IBookReadRepository bookReadRepository;
public GetAllBookQueryHandler(IBookReadRepository bookReadRepository)
{
this.bookReadRepository = bookReadRepository;
}
public async Task<List<GetAllBookQueryResponse>> Handle(GetAllBookQueryRequest request, CancellationToken cancellationToken)
{
List<B.Book> books = bookReadRepository.GetAll().Include(x=>x.Authors).Include(x=>x.Category).Include(x=>x.BookImages).ToList();
List<GetAllBookQueryResponse> responses = new();
foreach (B.Book book in books)
{
responses.Add(
new GetAllBookQueryResponse
{
Name= book.Name,
CategoryName=book.Category.Name,
AuthorName=book.Authors.First().Name,
Img=book.BookImages.First().Path,
UnitPrice=book.UnitPrice,
}
);
}
return responses;
}
}
GetAllBookQueryRequest
public class GetAllBookQueryRequest : IRequest<List<GetAllBookQueryResponse>>
{
//This place is empty as all books are requested
}
GetAllBookQueryResponse
public class GetAllBookQueryResponse
{
public int Id { get; set; }
public string Name { get; set; }
public string CategoryName { get; set; }
public string AuthorName { get; set; }
public string Img { get; set; }
public ushort UnitPrice { get; set; }
}
ServiceRegistration for IoC
using MediatR;
using Microsoft.Extensions.DependencyInjection;
namespace BookAPI.Application
{
public static class ServiceRegistration
{
public static void AddApplicationServices(this IServiceCollection services)
{
//find all handler, request and response and add IoC
services.AddMediatR(typeof(ServiceRegistration));
services.AddHttpClient();
}
}
}
Program.cs
I add services
builder.Services.AddApplicationServices();
Book Controller
.
.
.
readonly IMediator mediator;
public BookController(IBookWriteRepository bookWriteRepository, IWebHostEnvironment webHostEnvironment, IFileService fileService, IMediator mediator)
{
bookWriteRepository = bookWriteRepository;
_fileService = fileService;
this.mediator = mediator;
}
[HttpGet]
public async Task<IActionResult> GetAllBooks([FromQuery] GetAllBookQueryRequest getAllBookQueryRequest)
{
return Ok(await mediator.Send(getAllBookQueryRequest));
}
.
.
.
I guess it doesn't see the service I introduced, but I don't understand why GetAllBookHandler is throwing an error in the operation and not the others. For example, my handlers that list and create customers are working.