Question

Been at this for too long! any advice on the following problem…

code added:

Model: AccountModels.cs

[Required]
[Display(Name = "Select role: ")]
public String Role { get; set; }

Controller: AccountController.cs

  // GET: /Account/Register

public ActionResult Register()
{ 
    List<SelectListItem> list = new List<SelectListItem>();
    SelectListItem item; 
    foreach (String role in Roles.GetAllRoles()) 
    { 
        item = new SelectListItem { Text = role, Value = role }; 
        list.Add(item); 
    }
    ViewBag.roleList = (IEnumerable<SelectListItem>)list;
    return View();
}

Also in the [HTTpPost]

if (createStatus == MembershipCreateStatus.Success)
{
    Roles.AddUserToRole(model.UserName, model.Role);

    MailClient.SendWelcome(model.Email);
    FormsAuthentication.SetAuthCookie(model.UserName, false /* createPersistentCookie */);
    return RedirectToAction("Create", "Customers");
}

View: Register.cshtml

<div class="editor-label">      
    @Html.LabelFor(m => m.Role)  
</div>      
<div class="editor-field">
    @Html.DropDownListFor(m => m.Role, ViewBag.roleList as IEnumerable<SelectListItem>)

The code works and allows the user to select a role but falls apart if the user breaks validation rules when creating a new account.

Example: if the passwords don’t match normally validation would kick in but due to the addition of the new code the application just crashes.

The code which creates the error:

@Html.DropDownListFor(m => m.Role, ViewBag.roleList as IEnumerable<SelectListItem>)

Error code

The ViewData item that has the key ‘Role’ is of type ‘System.String’ but must be of type ‘IEnumerable’.

Answer 1

I guess you have this problem occuring when in your HttpPost action method where your Validation fails. and i believe you have return View() statement in your HttpPost action method. When you return the View again, your ViewData is null. So you need to reload the data again for the dropdown

public ActionResult Register()
{
 //If validation ok, save
 if (createStatus == MembershipCreateStatus.Success)
 {
   //dio stuff
 }
 else
 { 
    List<SelectListItem> list = new List<SelectListItem>();
    SelectListItem item; 
    foreach (String role in Roles.GetAllRoles()) 
    { 
        item = new SelectListItem { Text = role, Value = role }; 
        list.Add(item); 
    }
    ViewBag.roleList = (IEnumerable<SelectListItem>)list; 
    return View();
 }
}

Ideally, I would not use the ViewData to hande this. I will have my ViewModel to handle this.

public class RegisterViewModel
{
 public string FirstName { set;get;} 
 public IEnumerable<SelectListItem> Roles { get; set; }
 public int SelectedRoleId { get; set; }
}

and in your get action call,pass the ViewModel back to your View.

public ActionResult Register()
{
  RegisterViewModel objViewModel=new RegisterViewModel();
  objViewModel.Roles=GetAllRolesAs();  // returns the list of roles to this property
  return View(objViewModel);
}

Make your View a strongly typed one

@model RegisterViewModel
@using (Html.BeginForm())
{
   @Html.TextBoxFor(m => m.FirstName)

   @Html.DropDownListFor(x => x.SelectedRoleId,new SelectList(Model.Roles , "Value","Text"),   "Select Role")
  <input type="submit" value="Save" />
}

and in your HttpPostAction, Receive this ViewModel object as the parameter

[HttpPost]
public ActionResult Register(RegisterViewModel objVM)
{
  if(ModelState.IsValid)
  {
    //Check your custom validation also
    if (createStatus == MembershipCreateStatus.Success)
    {
          //Save and then Redirect

    }
    else
    {
      objVM.Roles=GetAllRolesAs(); // get the list of roles here again because HTTP is stateless
    }
  }  
 return View(objVM);
}