Question

i’d like to know how can I get a property like an entity, for example:

My Model:

public class Product {

   public int Id { get; set; }
   public string Name { get; set; }
   public Category Category { get; set; }

}

View:

Name: <%=Html.TextBoxFor(x => x.Name) %>
Category: <%= Html.DropDownList("Category", IEnumerable<SelectListItem>)ViewData["Categories"]) %>

Controller:

public ActionResult Save(Product product)
{
   /// produtct.Category ???
}

and how is the category property ? It’s fill by the view ? ASP.Net MVC know how to fill this object by ID ?

Thanks!

Answer 1

This is one of the reasons why it’s bad to bind directly to entities. Consider

public class ProductForm {
   public int Id { get; set; }
   public string Name { get; set; }
   public string CategoryId { get; set; }
}

public ActionResult Save(ProductForm form)
{
   var product = new Product
   {
        Id = form.Id,
        Name = form.Name,
        Category = database.GetCategory(form.CategoryId)
   };
}

In case of view models as above, it may be OK to use custom model binders to automatically get entities by Id from database. See here for sample implementation (in S#arp Architecture) that binds IDs to entities from database. But I think for now you better go with simpler implementation like above.

You can also use AutoMapper to simplify form->entity mapping.