ASP.Net MVC: How to bind dropdown with deep nested property - asp.net-mvc-4

Question

suppose below is my view model classes.
public class MainViewModel
{
public List<Student> Students { get; set; }
public int SelectedState = 0;
}
public class Student
{
public int ID = 0;
public string Name = "";
public int StateID = 0;
public List<States> States { get; set; }
}
public class States
{
public int ID = 0;
public string Name = "";
}
now how could i bind dropdown with nested property called States of student class ?
#Html.DropDownListFor(x => x.SelectedState new SelectList(Model.Students.States, "ID", "Name", Model.SelectedState), "-- Select States--", new { id = "cboState", #class = "edit-mode" })
this is not working SelectList(Model.Students.States, "ID", "Name", Model.SelectedState) how to refer this Model.Students.States
please discuss this issue with code sample. each student has relation with states.

Answer 1

Check this out:
#Html.DropDownListFor(x => x.SelectedState, new SelectList(Model.Students.FirstOrDefault().States, "ID", "Name", Model.SelectedState), "-- Select States--", new { id = "cboState", #class = "edit-mode" })
But its better to save States List in ViewBag in your Controller:
ViewBag.States = (_context or _serviceLayer).(States or GetStates()).Select(s => new SelectListItem { Value = s.ID, Text = s.Name, Selected = s.ID == viewModel.SelectedState }).ToList();
And on View:
#Html.DropDownListFor(x => x.SelectedState, (List<SelectListItem>)ViewBag.States, "-- Select States--", new { id = "cboState", #class = "edit-mode" })
REQUESTED EDIT:
Models:
namespace MyProject.Models
{
public class ViewInfo
{
public int StateID { get; set; }
}
public class Student
{
public int ID { get; set; }
public string FullName { get; set; }
public int StateID { get; set; }
}
public class State
{
public int ID { get; set; }
public string Name { get; set; }
}
}
Controllers:
using MyProject.Models;
namespace MyProject.Controllers
{
public class StudentsController : Controller
{
private MyDBEntities _context;
public StudentsController()
{
this._context = new MyDBEntities();
}
// StudentsController
public ActionResult Index()
{
ViewBag.ViewInfo = new ViewInfo { StateID = 1 };
ViewBag.StateID = _context.States.Select(s => new SelectListItem { Value = s.ID, Text = s.Name }).ToList();
return View(_context.Students.ToList());
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Index(ViewInfo viewInfo)
{
ModelState.Clear();
ViewBag.ViewInfo = viewInfo;
ViewBag.StateID = _context.States.Select(s => new SelectListItem { Value = s.ID, Text = s.Name, Selected = s.ID == viewInfo.StateID }).ToList();
return View(_context.Students.Where(s => s.StateID == viewInfo.StateID).ToList());
}
}
}
And the View:
#using MyProject.Models;
#model IEnumerable<MyProject.Models.Student>
#{
ViewBag.Title = "Students";
ViewInfo viewInfo = ViewBag.ViewInfo;
}
<div class="page-header">
<h2>Students</h2>
</div>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken();
#Html.DropDownList("StateID", null, new { #class = "form-control" })
<input type="submit" value="Filter" class="btn btn-primary" />
// Students Table
}