Create ViewData outside Controler in MVC - model-view-controller

Question

I have a method inside a controller that creates ViewData. For example this one
private void CreateFKViewData(OSQDCOL osqdcol, OSADCOL osadcol, IList<OSADCOL> targetTBLcols)
{
...
ViewData[osadcol.ColName] = new SelectList(SelectListItems, "key", "value", SelectListItems.First().Key);
}
If that method is placed inside the controller everything works as expected. I want to move that method outside my controller and place it into a different class in my BLL layer. The problem is that ViewData is not accessible outside the scope of the controller.
Any ideas?

Answer 1

I'm assuming you're using ASP.NET MVC and C#. Not sure it's a great idea to spread around concerns that a controller would normally do into classes outside of the controller, but suffice to say that the reason for your issue is that ViewData is made available by the fact that your controller class inherits from Controller which in turn inherits from ControllerBase (which is where ViewData is provided). So let's say you wanted to call a method in another class from your controller, and you wanted that method to be able to manipulate ViewData. Consider the following:
public class TestController : Controller
{
// GET: Test
public ActionResult Index()
{
var externalclass = new SomeRandomClass(this);
externalclass.DoStuff();
return View();
}
}
public class SomeRandomClass
{
ControllerBase _callingController = null;
public SomeRandomClass(ControllerBase callingController)
{
this._callingController = callingController;
}
public void DoStuff()
{
this._callingController.ViewData["hello"] = "world";
}
}