Posting Data on a ViewModel with a Constructor with Parameters

If you ever get into a MVC ViewModel Error - No parameterless constructor defined for this object, then you got into a situation where you have a viewmodel that needs parameters. Example:

namespace Application.Web.Models
{
    public class GameweekViewModel
    {
        public virtual IEnumerable<Book> BookList { get; set; }

        public BookSheelViewModel(IStoreDataSource db)
        {
            this.BookList = db.Books.ToList();
        }
    }
}

Once you post this model back to the controller, MVC will need to create a new instance and will not know how to. The easiest solution is to add a parameterless constructor to the Viewmodel:

namespace Application.Web.Models
{
    public class GameweekViewModel
    {
        public virtual IEnumerable<Book> BookList { get; set; }

        public BookSheelViewModel() {  }

        public BookSheelViewModel(IStoreDataSource db)
        {
            this.BookList = db.Books.ToList();
        }
    }
}

Another Solution is to use an IoC (Inversion of control) framework that handles the dependency injection for you.