There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key '****'. [duplicate] - asp.net-mvc-4

Question

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The ViewData item that has the key 'XXX' is of type 'System.Int32' but must be of type 'IEnumerable<SelectListItem>'
(6 answers)
Closed 4 years ago.
Im trying to do a dropdownlist of Student Enrollments at Student index page.
Student Controller:
public ActionResult Index(string studentEnrollment, string sortOrder, string currentFilter, string searchString, int? page)
{
ViewBag.CurrentSort = sortOrder;
ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";
ViewBag.DateSortParm = sortOrder == "Date" ? "date_desc" : "Date";
if (searchString != null)
{
page = 1;
}
else
{
searchString = currentFilter;
}
ViewBag.CurrentFilter = searchString;
var students = studentService.GetAll();
//var students = from s in studentService.GetAll()
// select s;
var studentViewModel = Mapper.Map<IEnumerable<Student>, IEnumerable<StudentViewModel>>(students);
if (!String.IsNullOrEmpty(searchString))
{
students = students.Where(s => s.LastName.ToUpper().Contains(searchString.ToUpper())
|| s.FirstMidName.ToUpper().Contains(searchString.ToUpper()));
}
switch (sortOrder)
{
case "name_desc":
students = students.OrderByDescending(s => s.LastName);
break;
case "Date":
students = students.OrderBy(s => s.EnrollmentDate);
break;
case "date_desc":
students = students.OrderByDescending(s => s.EnrollmentDate);
break;
default:
students = students.OrderBy(s => s.LastName);
break;
}
List<Course> courses = new List<Course>();
SelectList studentEnrollment = new SelectList(courses, "CourseID", "Title");
ViewBag.Courses = studentEnrollment;
//if (!string.IsNullOrEmpty(studentEnrollment))
// students = students.Where(m => m.Course.Title == studentEnrollment);
int pageSize = 3;
int pageNumber = (page ?? 1);
return View(students.ToPagedList(pageNumber, pageSize));
}
View:
#using (Html.BeginForm("Index", "Student", FormMethod.Get))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<p>
Find by name: #Html.TextBox("SearchString", ViewBag.CurrentFilter as string)
Enrollment: #Html.DropDownList("Course", (IEnumerable<SelectListItem>)ViewBag.Courses, "Select Course")
<input type="submit" value="Filter" />
</p>
}
error at line:
Enrollment: #Html.DropDownList("Course", (IEnumerable)ViewBag.Courses, "Select Course")
What Im doing wrong?

Answer 1

I have seen a lot of questions where people have had issues with the drop down list and it was because of the view bag. Everything I have seen says you should try to avoid using ViewBag for drop downs. What I would suggest instead is to put your list in your viewmodel.
Public List<SelectListItem> CourseList { get; set; }
I am not seeing in your code where you are populating your course list. On your controller instead of setting the viewbag set this parameter. Something like
foreach(var temp in CourseList){ //Course list being pulled from the database or wherever that data exists
model.CourseList.Add(new SelectListItem{ Text = temp.Name, Value = temp.Value });
}
then on your view your drop down list would be changed to
#Html.DropDownList("Course", Model.CourseList, "Select Course")