Automatically resolve concrete class without configuration in .NET Core?

Question

I'm porting a project from .NET 4.52 to .NET Core. This project has previously used Structuremap for dependency injection and in structuremap you don't need to configure concrete types to enable dependency injection. Is there any way to do this with the built in dependency injection in .NET Core?

Answer 1

If you are trying to resolve a concrete type and have its dependencies injected from the IoC container then the following extension function may be of use to you. This makes the assumption that all dependencies of the concrete type can be resolved through the container.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace Microsoft.Extensions.DependencyInjection
{
    public static class ServiceProviderExtensions
    {
        public static TService AsSelf<TService>(this IServiceProvider serviceProvider, params object[] overrides)
        {
            return (TService)AsSelf(serviceProvider, typeof(TService), overrides);
        }
        public static object AsSelf(this IServiceProvider serviceProvider, Type serviceType, params object[] overrides)
        {
            // ref: https://docs.microsoft.com/en-us/dotnet/api/microsoft.extensions.dependencyinjection.activatorutilities.createinstance?view=dotnet-plat-ext-5.0#definition
            // ref: https://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs#L108-L118

            return ActivatorUtilities.CreateInstance(serviceProvider, serviceType, overrides);
        }
    }
}