How to post dropdownlist viewbag values to sql server using mvc 4? - asp.net-mvc-4

Question

I am getting dynamic values in dropdownlist through viewbag,dropdownlist values is displaying properly but my problem is posting,I am getting problem to insert dropdownlist values in sql server,please help me to solve this problem.
This is my model page,
public class RegisterModel
{
public Prefix Prefix { get; set; }
}
public class Prefix
{
public int? ID { get; set; }
public string Name { get; set; }
}
This is my controller page,
void BindPrefix()
{
List<Prefix> lstPrefix = new List<Prefix>()
{
new Prefix { ID = null, Name = "Select" },
new Prefix { ID = 1, Name = "Mr" },
new Prefix { ID = 2, Name = "Ms" },
new Prefix { ID = 1, Name = "Mrs" },
new Prefix { ID = 2, Name = "Dr" }
};
ViewBag.Prefix = lstPrefix;
}
public ActionResult Register()
{
BindPrefix();
return View();
}
[HttpPost]
public ActionResult Register(FormCollection FC)
{
string Prefix =FC[ViewBag.Prefix]; // here prefix get null value.
return view();
}
This is my view page,
#Html.DropDownListFor(m => m.Prefix.ID, new SelectList(ViewBag.Prefix, "ID", "Name", ViewBag.pef))

Answer 1

If you are trying to get Selected Value,You have to get from the Drop down name which generate:
string Prefix =FC["Prefix"];
Currently this :
#Html.DropDownListFor(m => m.Prefix.ID, new SelectList(ViewBag.Prefix, "ID", "Name", ViewBag.pef))
will generate this html:
<select id="Prefix_ID" name="Prefix.ID">
.........
.........
</select>
and using Element name in form Collection will give you the value.
string Prefix =FC["Prefix.ID"].ToString();

Answer 2

Based on the comments that you only want to display and post back a 'title', the use of class Prefix seems unnecessary
View model
public class RegisterViewModel
{
[Required(ErrorMessage = "Please select a title")]
public string Title { get; set }
// other properties
public SelectList TitleList { get; set; }
}
Controller
public ActionResult Register()
{
RegisterViewModel model = new RegisterViewModel();
ConfigureViewModel(model);
return View(model);
}
[HttpPost]
public ActionResult Register(RegisterViewModel model)
{
if(!ModelState.IsValid)
{
ConfigureViewModel(model);
return View(model);
}
// save and redirect
}
private void ConfigureViewModel(RegisterViewModel model)
{
List<string> titles = new List<string>) { "Mr.", "Ms", "Mrs", "Dr." };
model.TitleList = new SelectList(titles);
}
View
#model RegisterViewModel
...
#using (Html.BeginForm())
{
#Html.LabelFor(m => m.Title)
#Html.DropDownListFor(m => m.Title, Model.TitleList, "-Please select-")
#Html.ValidationMessageFor(m => m.Title)
....
}