MediatR DI registration Issue for Service Fabric application-CodePudding

I'm trying to implement MediatR in a Service Fabric application running on core 3.1. I'm able to wire up the Queryhandler as long as I don't include a repository (which really defeats the purpose).

Thank you for taking a look!

Here is how I am setting up the DI. in Main() I have:

                var assembly1 = Assembly.GetExecutingAssembly();
                var assembly2 = typeof(GetSomeThingQuery).Assembly;
                var assembly3 = typeof(IRepository<myDto>).Assembly;
                var assembly4 = typeof(myDto).Assembly;
                
                var provider = new ServiceCollection()
                    .AddLogging()
                    .AddMediatR(assembly1, assembly2, assembly3, assembly4)
                    .AddSingleton<IApiExceptionService, ApiExceptionService>()
                    .BuildServiceProvider();

                ServiceRuntime.RegisterServiceAsync("ApiServiceType",
                    context => new ApiService(context, provider.GetService<IApiExceptionService>(), provider.GetService<IMediator>())).GetAwaiter().GetResult();

My handler looks like:



namespace Query
{
    public class GetSomeThingQuery: IRequest<List<myDto>>
    {
        public string para1{ get; set; }
        public string para2 { get; set; }
    }

    public class GetSomeThingQueryHandler : IRequestHandler<GetSomeThingQuery, List<myDto>>
    {


        private readonly IRepository<myDto> _repository;

        public GetSomeThingQueryHandler (IRepository<myDto> repository)
        {
            _repository = repository;
        }


        public async Task<List<myDto>> Handle(GetSomeThingQueryHandler Query request, CancellationToken cancellationToken)
        {
            var test =  await _repository.CallTheDatabaseAndGetTheResult(request.para1);
            return null; //this is just here as a place holder.
        }
    }
}

The error I get is:

System.InvalidOperationException: Error constructing handler for request of type MediatR.IRequestHandler`2[Query.GetSomeThingQuery,System.Collections.Generic.List`1[Sql.myDto]]. Register your handlers with the container. See the samples in GitHub for examples.
 ---> System.InvalidOperationException: Unable to resolve service for type 'IRepository`1[myDto]' while attempting to activate 'Query.GetSomeThingQuery'.
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.CreateArgumentCallSites(Type serviceType, Type implementationType, CallSiteChain callSiteChain, ParameterInfo[] parameters, Boolean throwIfCallSiteNotFound)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.CreateConstructorCallSite(ResultCache lifetime, Type serviceType, Type implementationType, CallSiteChain callSiteChain)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.TryCreateExact(ServiceDescriptor descriptor, Type serviceType, CallSiteChain callSiteChain, Int32 slot)

I have tried various ways of setting put the container but nothing has worked. If I remove the following lines, MediatR can resolve the handler. When I include the repo it can't resolve the handler.

        private readonly IRepository<myDto> _repository;

        public GetSomeThingQueryHandler (IRepository<myDto> repository)
        {
            _repository = repository;
        }

CodePudding user response：

You need to add all the classes that you're going to use in the DI container. You haven't registered the repository.

You need to add:

.AddScoped(typeof(IRepository<>), typeof(Repository<>));

to your ServiceCollection.

I recommend Scrutor to help with the registration if you don't want to register your classes one by one.