Problems with Partial Views in ASP.NET MVC 2

I think you should create an ActionFilter and apply it on your controllers.

Create an action filter like this

public class DataForMasterPageAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        //initiate your repository

           var catRepository = ...;

        //then create the viewdata like so

        filterContext.Controller.ViewData["Categorias"] = new SelectList(catRepository.FindAllCategorias().AsEnumerable(), "id", "nome", 3);
    }

}

Then apply it on the controller and it will be available for all actions as well. Like so;

[DataForMasterPage]
public class CategoriaController : Controller
{
      public ActionResult Index()
      {
            ViewData["Message"] = "Welcome to ASP.NET MVC!";
            return View();
      }
}

On the partial view you just call the ViewData as usual, no need to change anything

<div class="editor-label">
        <%= Html.LabelFor(model => model.categoria_id) %>
    </div>
    <div class="editor-field">
        <%= Html.DropDownListFor(model => model.categoria_id, (SelectList)ViewData["Categorias"], "--Selecciona um--")%>

        <%= Html.ValidationMessageFor(model => model.categoria_id) %>
    </div>

Might have performance issues, but its one of the simplest ways to avoid setting the ViewData on every method.

You can create base class for your controllers and set it during creation if you need to query for it with every request:

public class BaseController : Controller
{
    public BaseController()
    {
        var catRepository = ...;
        ViewData["Categoriass"] = new SelectList(catRepository.FindAllCategorias().AsEnumerable(), "id", "nome", 3);
    }
}

That is not really efficient,because it will be executed with every controller. You can also create action filter which sets ViewData and apply it where needed.

I have try Nick Masao & LukLed solutions, both of them are works.

However, the viewdata is set for masterpage, in my case, i assume masterpage will render every page.

I have to apply the [DataForMasterPage] attribute (Nick Masao's solutions) or or inherits the BaseController (LukLed's solutions) on every View's Controller.

So, is it possible create a Class and invoke on Global.asax Application_Start event to make it Set viewdata everytimes?

You could also create a ContentPlaceHolder where you want the partial view to render and call the RenderPartial() from the underlying pages. That way you can pass the model as usual.