cli-ninject-hosting/CustomHostingDemo/NinjectCommandHandler.cs

using Ninject;
using Ninject.Parameters;
using System;
using System.CommandLine.Binding;
using System.CommandLine.Invocation;
using System.Threading.Tasks;

namespace CustomHostingDemo
{
    public interface ICommandHandler<TArg>
    {
        Task<int> InvokeAsync(InvocationContext context, TArg args);
    }

    public class NinjectCommandHandler<TArg> : ICommandHandler
    {
        private readonly IKernel _kernel;
        private readonly Type _handlerType;

        public NinjectCommandHandler(IKernel kernel, Type handlerType)
        {
            _kernel = kernel;
            _handlerType = handlerType;

            if (!typeof(ICommandHandler<TArg>).IsAssignableFrom(_handlerType))
            {
                throw new ArgumentException($"The handler type must implement ICommandHandler<{typeof(TArg).Name}>", nameof(handlerType));
            }
        }

        public Task<int> InvokeAsync(InvocationContext context)
        {
            var cmdArgs = _kernel.Get<TArg>();
            var binder = new ModelBinder<TArg>();
            binder.UpdateInstance(cmdArgs, context.BindingContext);

            var handler = (ICommandHandler<TArg>)_kernel.Get(_handlerType, new Parameter(nameof(InvocationContext), context, shouldInherit: true));
            return handler.InvokeAsync(context, cmdArgs);
        }
    }
}