How to resolve generic interface to generic implementation when using dependency injection?

问题

I have created a generic repository that I want to be used in a service.

public abstract class AbstractBaseRepository<TEntity, TEntityKey>
        : IBaseRepository<TEntity, TEntityKey>
        where TEntity : class, IBaseEntity<TEntityKey>, new() { /* some code */ }

And the interface:

public interface IBaseRepository<TEntity, TEntityKey> { /* some code */ }

On my service I inject the repository like this:

public class TenantsService : AbstractBaseService<TenantEntity, int>
{
    public TenantsService(IBaseRepository<TenantEntity, int> tenantsRepository)
        : base(tenantsRepository) { }
}

On my startup, on the ConfigureServices method, I have:

services.AddScoped(typeof(IBaseRepository<,>), typeof(AbstractBaseRepository<,>));

I added this startup code based on the following two answers:

https://stackoverflow.com/a/33567396

https://stackoverflow.com/a/43094684

When I run the application I am getting the following error:

Cannot instantiate implementation type 'Playground.Repositories.Base.AbstractBaseRepository`2[TEntity,TEntityKey]' for service type 'Playground.Repositories.Base.IBaseRepository`2[TEntity,TEntityKey]'

回答1:

Try this:

services.AddScoped(typeof(IBaseRepository<TenantEntity, int>), typeof(TenantsService));

As Kirk Larkin mentioned in the comments, you're telling it to instantiate an abstract class for services.AddScoped(typeof(IBaseRepository<,>), typeof(AbstractBaseRepository<,>)); which it can't do.

来源：https://stackoverflow.com/questions/53101127/how-to-resolve-generic-interface-to-generic-implementation-when-using-dependency

标签

asp.net-core

dependency-injection