Please don't use above way.Always try to use ViewModel with your views.Put all your data annotations on that ViewModel and check that inside the action method.
Plese check below mentioned sample ViewModel as an example.
public class ProductViewModel
{
public Guid Id { get; set; }
[Required(ErrorMessage = "required")]
public string ProductName { get; set; }
public int SelectedValue { get; set; }
public virtual ProductCategory ProductCategory { get; set; }
[DisplayName("Product Category")]
public virtual ICollection<ProductCategory> ProductCategories { get; set; }
}
Inside the Action Method:
[HttpPost]
public ActionResult AddProduct(ProductViewModel productViewModel) //save entered data
{
//get product category for selected drop down list value
var prodcutCategory = Repository.GetProductCategory(productViewModel.SelectedValue);
//for get all product categories
var prodcutCategories = Repository.GetAllProductCategories();
//for fill the drop down list when validation fails
productViewModel.ProductCategories = prodcutCategories;
//for initialize Product domain model
var productObj = new Product
{
ProductName = productViewModel.ProductName,
ProductCategory = prodcutCategory,
};
if (ModelState.IsValid) //check for any validation errors
{
//save recived data into database
Repository.AddProduct(productObj);
return RedirectToAction("AddProduct");
}
else
{
//when validation failed return viewmodel back to UI (View)
return View(productViewModel);
}
}