Unable to get my ASP.NET Core Web API Interface working with my-CodePudding

Here is the error I am receiving when I try to execute an insert into my SQL database on .NET:

System.InvalidOperationException: Unable to resolve service for type 'MotionPicturesCore.Interfaces.IMotionPictureService' while attempting to activate 'MotionPicturesCore.Controllers.MotionPictureApiControllerV2'.

at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
at lambda_method55(Closure , IServiceProvider , Object[] )
at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass7_0.b__0(ControllerContext controllerContext)
at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass6_0.g__CreateController|0(ControllerContext controllerContext)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()

I am not sure why I am getting this error aside from the fact that I believe it may have to do with how I have set up my dependency injection. Eventually, this will be hooked up to a simple Vue.js application but for right now, this API I have built is shooting back this error at me.

Here are snippets from what I believe to be where my error in setting this up may be but again, I am not sure. I don't want to post whole blocks of code for anyone to sift through but if someone can point me in the right direction, it would be more than appreciated:

namespace MotionPicturesCore.Interfaces
{
    public interface IMotionPictureService
    {
        int AddMotionPicture(MotionPictureAddRequest model);
        void UpdateMotionPicture(MotionPictureUpdateRequest model);
        MotionPicture GetSingleMotionPicture(int id);
        List<MotionPicture> GetAllMotionPictures();
        void DeleteMotionPicture(int id);
    }
}

namespace MotionPicturesCore.StartUp
{
    public class DependencyInjection
    {
        public static void ConfigureServices(IServiceCollection services, IConfiguration configuration)
        {
            if (configuration is IConfigurationRoot)
            {
                services.AddSingleton<IConfigurationRoot>(configuration as IConfigurationRoot);  
            }

            services.AddSingleton<IConfiguration>(configuration); 

            string connString = configuration.GetConnectionString("Default");

            services.AddSingleton<IDataProvider, SqlDataProvider>(delegate (IServiceProvider provider)
            {
                return new SqlDataProvider(connString);
            });

            services.AddSingleton<IMotionPictureService, IMotionPictureService>();

            GetAllEntities().ForEach(tt =>
            {
                IConfigureDependencyInjection idi = Activator.CreateInstance(tt) as IConfigureDependencyInjection;
                idi.ConfigureServices(services, configuration);
            });
        }

        public static List<Type> GetAllEntities()
        {
            return AppDomain.CurrentDomain.GetAssemblies().SelectMany(x => x.GetTypes())
                 .Where(x => typeof(IConfigureDependencyInjection).IsAssignableFrom(x) && !x.IsInterface && !x.IsAbstract)
                 .ToList();
        }

        public static void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
        }
    }
}

CodePudding user response：

In your DI configuration, you setup up IMotionPictureService to use an instance of IMotionPictureService - notice the I that marks the interface:

services.AddSingleton<IMotionPictureService, IMotionPictureService>();

The configuration usually is like this:

services.AddSingleton<IMotionPictureService, MotionPictureService>();

This way, you bind the implementation MotionPictureService to the interface IMotionPictureService.

CodePudding user response：

i think i found ur error.

this line services.AddSingleton<IMotionPictureService, IMotionPictureService>();

should be something like services.AddSingleton<IMotionPictureService, MotionPictureService>();

You are binding your interface to same interface. U need to bind it to a class, like MotionPictureService for exemple.

CodePudding user response：

You have to create a class to use as implementation, you can't pass for both type arguments of AddSingleton IMotionPictureService.

You need to create a class MotionPictureService which inherits from the interface IMotionPictureService and then you can register your singleton as such:

services.AddSingleton<IMotionPictureService, MotionPictureService>();