error while display role name in a view - asp.net-mvc-4

Question

i , Actually want to display a role name in place of role id
so i'm doing this
these are my model's
[Table("User")]
public class User
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int UserId { get; set; }
[Required(ErrorMessage = "Please Provide Fullname", AllowEmptyStrings = false)]
[Display(Name = "Full Name")]
public string Full_Name { get; set; }
[Required(ErrorMessage = "Please Provide Username", AllowEmptyStrings = false)]
public string Username { get; set; }
[Required(ErrorMessage = "Please provide password", AllowEmptyStrings = false)]
[DataType(System.ComponentModel.DataAnnotations.DataType.Password)]
public string Password { get; set; }
[Required(ErrorMessage = "Please Select User type", AllowEmptyStrings = false)]
[Display(Name = "USER TYPE")]
public int ROLEID { get; set; }
[Required(ErrorMessage = "Please Select Login Status", AllowEmptyStrings = false)]
[Display(Name = "Login Status")]
public string Login_Status { get; set; }
public List<Role> role { get; set; }
UserDB db = new UserDB();
public Role getname(int id) {
return db.roles.SingleOrDefault(d => d.ROLEID == id);
}
}
[Table("ROLE")]
public class Role
{
public int ROLEID { get; set; }
public string ROLENAME { get; set; }
}
public class UserRole
{
public List<User> Ruser { get; set; }
public List<Role> Rrole { get; set; }
}
this is my controller
public ActionResult Userlist(int? page)
{
UserDB dc = new UserDB();
List<User> users = dc.users.ToList();
UserRole userrole = new UserRole();
userrole.Ruser = users;
return View(userrole);
}
this is my view
#model PHARMACY.Models.UserRole
<table class="table table-striped table-hover ">
<tr>
<th>
#Html.DisplayNameFor(model => model.Ruser.First().Full_Name)
</th>
<th>
#Html.DisplayNameFor(model => model.Ruser.First().Username)
</th>
<th>
#Html.DisplayNameFor(model => model.Ruser.First().Password)
</th>
<th>
#Html.DisplayNameFor(model => model.Rrole.First().ROLENAME)
</th>
<th>
#Html.DisplayNameFor(model => model.Ruser.First().Login_Status)
</th>
<th></th>
</tr>
#foreach (var item in Model.Ruser) {
<tr>
<td>
#Html.DisplayFor(modelItem => item.Full_Name)
</td>
<td>
#Html.DisplayFor(modelItem => item.Username)
</td>
<td>
#Html.DisplayFor(modelItem => item.Password)
</td>
<td>
#{
var name = Model.Rrole.Where(i => i.ROLEID == item.ROLEID);
#Html.DisplayFor(m => m.Rrole.Where(i => i.ROLEID == item.ROLEID).FirstOrDefault());
}
</td>
<td>
#Html.DisplayFor(modelItem => item.Login_Status)
</td>
<td>
<p class="label label-info">#Html.ActionLink("Edit", "EditUser", new { id=item.UserId,})</p> |
<p class="label label-danger">#Html.ActionLink("Delete", "DeleteUser", new { id=item.UserId })</p>
</td>
</tr>
}
</table>
But it through an error that "Value cannot be null.
Parameter name: source"

Answer 1

If you have no users in your database, this line will cause the error:
#Html.DisplayNameFor(model => model.Ruser.First().Full_Name)
You are not handling the case where model.Ruser is empty.