model_binder.cs

namespace MyProject.Web.Binders{
  using System.Web.Mvc;
  using Domain;
  public class RootBinder<TRoot,TRepository>:DefaultModelBinder
    where TRepository:IRepository<TRoot> where TRoot:IRoot{
    private readonly TRepository _repository;
    public RootBinder(TRepository repository){
      Guard.AgainstNull(repository);
      _repository=repository;
    }
    public override object BindModel(ControllerContext controllerContext,ModelBindingContext bindingContext){
      if(bindingContext.ModelType!=typeof(TRoot))
        return base.BindModel(controllerContext,bindingContext);
      var vp=bindingContext.ValueProvider;
      var v=vp.GetValue(bindingContext.ModelName)??vp.GetValue("id");
      var id=int.Parse(v.AttemptedValue);
      return _repository.Get(id);
    }
    }
}