How can a view use a model that uses generics?

Question

In MVC 3, I've been refactoring my controllers to remove some duplicate code by using generics which I was successful in doing, but now I'm trying to refactor my views, but I can't seem to adjust the model that the view uses to use generics.

Here is the relevant portion of my refactored abstract base controller:

public abstract class CrudController<TEntity> : Controller where TEntity : Entity, INamedEntity, IOrderedEntity, IHasMembers, new()
{
  private readonly IUnitOfWork _unitOfWork;
  protected readonly IRepository<TEntity> Repository;

  protected CrudController(IUnitOfWork unitOfWork)
  {
    _unitOfWork = unitOfWork;
    Repository = _unitOfWork.RepositoryFor<TEntity>();
  }

  public ActionResult Edit(int id)
  {
    return PartialView(Repository.FindById(id));
  }

  // More actions here...
}

Here are my actual controllers (they are really basic since the refactoring):

public class StatusController : CrudController<MemberStatus>
{
  public StatusController(IUnitOfWork unitOfWork) : base(unitOfWork)
  {
  }
}

public class PositionController : CrudController<MemberPosition>
{
  public PositionController(IUnitOfWork unitOfWork) : base(unitOfWork)
  {
  }
}

Note that both MemberStatus and MemberPosition implement 'Entity, INamedEntity, IOrderedEntity, IHasMembers'

Now here are my Edit views for those two controllers which I want to refactor:

@model MyApp.Domain.Entities.MemberStatus
@using (Html.BeginForm("Save", @ViewContext.RouteData.Values["Controller"].ToString(), FormMethod.Post, new { id = "EntityForm" }))
{
  @Html.Hidden("Id")
  <label class="Name">
    <span>New Name:</span><br />
    @Html.EditorFor(x => x.Name)
  </label>
}

@model MyApp.Domain.Entities.MemberPositions
@using (Html.BeginForm("Save", @ViewContext.RouteData.Values["Controller"].ToString(), FormMethod.Post, new { id = "EntityForm" }))
{
  @Html.Hidden("Id")
  <label class="Name">
    <span>New Name:</span><br />
    @Html.EditorFor(x => x.Name)
  </label>
}

You can see that the views are almost identical, with the exception of the first line which declares the model. I want to find out how to pass in a generic parameter like I did with the controllers, which I thought (in my naivete) would look something like the following, but this obviously doesn't work.

@model <TEntity> where TEntity : Entity, INamedEntity, IOrderedEntity, IHasMembers, new()

How can I refactor these two views (by putting a generic view in the Shared folder) that would implement a non-concrete model in the view? Any suggestions are appreciated.

FYI - I think (though I haven't tried) that I could use a ViewModel, but I would prefer not to have to do that in this case (as I would have to implement the mapping from the entities to the ViewModel for each entity which somewhat defets the purpose of this refactoring).

Answer 1

If both of your models have common properties, create an interface with those properties in the interface, then make both models implement that interface. Now create a view that's strongly-typed to that interface. Another option is simply just a weakly-typed view that is dynamically evaluated at runtime.

Answer 2

Could you just have the model defined as whichever interface you're using rather than an object which implements many interfaces?:

@model INamedEntity
@using (Html.BeginForm("Save", @ViewContext.RouteData.Values["Controller"].ToString(), FormMethod.Post, new { id = "EntityForm" }))
{
 @Html.EditorForModel()
}

For this you can create an editor template for the INamedEntity interface.

Answer 3

@model Entity
@if (Model is INamedEntity)
{
  @{ Html.RenderPartial("NamedEntityFields", (INamedEntity)Model); }
}
@if (Model is IOrderedEntity)
{
  @{ Html.RenderPartial("OrderedEntityFields", (IOrderedEntity)Model); }
}

NamedEntityFields.cshtml:

@model INamedEntity
@* put name specific fields here *@