Bestpractice DI with ASP.NET MVC and StructureMap - How to inject dependencies in an ActionResult

I edited my whole question, so do not wonder :)

Well, I want to have an ActionResult that takes domain model data and some additional parameters, i.e page index and page size for paging a list. It decide itself if it returns a PartialViewResult or a ViewResult depending on the kind of web request (ajax request or not).

The reffered data shall be mapped automatically by using an IMappingService, which is responsible for transforming any domain model data into a view model. The MappingService uses AutoMapper for simplicity.

MappingActionResult:

public abstract class MappingActionResult : ActionResult
{
    public static IMappingService MappingService;
}

BaseHybridViewResult:

public abstract class BaseHybridViewResult : MappingActionResult
{
    public const string defaultViewName = "Grid";

    public string ViewNameForAjaxRequest { get; set; }
    public object ViewModel { get; set; }

    public override void ExecuteResult(ControllerContext context)
    {
        if (context == null) throw new ArgumentNullException("context");
        var usePartial = ShouldUsePartial(context);
        ActionResult res = GetInnerViewResult(usePartial);

        res.ExecuteResult(context);
    }

    private ActionResult GetInnerViewResult(bool usePartial)
    {
        ViewDataDictionary viewDataDictionary = new ViewDataDictionary(ViewModel);
        if (String.IsNullOrEmpty(ViewNameForAjaxRequest))
        {
            ViewNameForAjaxRequest = defaultViewName;
        }

        if (usePartial)
        {
            return new PartialViewResult { ViewData = viewDataDictionary, ViewName = ViewNameForAjaxRequest };
        }

        return new ViewResult { ViewData = viewDataDictionary };
    }

    private static bool ShouldUsePartial(ControllerContext context)
    {
        return context.HttpContext.Request.IsAjaxRequest();
    }
}

AutoMappedHybridViewResult:

public class AutoMappedHybridViewResult<TSourceElement, TDestinationElement> : BaseHybridViewResult
{
    public AutoMappedHybridViewResult(PagedList<TSourceElement> pagedList)
    {
        ViewModel = MappingService.MapToViewModelPagedList<TSourceElement, TDestinationElement>(pagedList);
    }

    public AutoMappedHybridViewResult(PagedList<TSourceElement> pagedList, string viewNameForAjaxRequest)
    {
        ViewNameForAjaxRequest = viewNameForAjaxRequest;
        ViewModel = MappingService.MapToViewModelPagedList<TSourceElement, TDestinationElement>(pagedList);
    }

    public AutoMappedHybridViewResult(TSourceElement model)
    {
        ViewModel = MappingService.Map<TSourceElement, TDestinationElement>(model);
    }

    public AutoMappedHybridViewResult(TSourceElement model, string viewNameForAjaxRequest)
    {
        ViewNameForAjaxRequest = viewNameForAjaxRequest;
        ViewModel = MappingService.Map<TSourceElement, TDestinationElement>(model);
    }
}

Usage in controller:

public ActionResult Index(int page = 1)
{
    return new AutoMappedHybridViewResult<TeamEmployee, TeamEmployeeForm>(_teamEmployeeRepository.GetPagedEmployees(page, PageSize));
}

So as you can see the IMappingService is hidden. The controller should not know anything about the IMappingService interface, when AutoMappedHybridViewResult is used.

Is the MappingActionResult with the static IMappingServer appropriate or am I violating the DI principle?

I think a better design is to have a ViewResultFactory that depends on IMappingService, then you can inject that into your controller. Then you call it like so:

public class MyController : Controller
{
    IViewResultFactory _viewResultFactory;
    ITeamEmployeeRepository _teamEmployeeRepository;

    public MyController(IViewResultFactory viewResultFactory)
    {
        _viewResultFactory = viewResultFactory;
    }

    public ActionResult MyAction(int page, int pageSize)
    {
        return
            _viewResultFactory.GetResult<TeamEmployee, TeamEmployeeForm>(
                _teamEmployeeRepository.GetPagedEmployees(page, pageSize));
    }
}

The implementation would like this (you would need to create overloads for each of your HybridViewResult constructors):

public HybridViewResult<TSourceElement, TDestinationElement> GetResult<TSourceElement, TDestinationElement>(PagedList<TSourceElement> pagedList)
{
    return new HybridViewResult<TSourceElement, TDestinationElement>(_mappingService, pagedList);
}

That way you hide the implementation from your controllers, and you don't have to depend on the container.