Select Tag Helper: asp-for

Question

Hello,

 

I'm constructing a view where I render the complete list of the classes grouped on a ViewModel. These are Stores and Departments (as cities).

 

I have a problem when I'm constructing the view, since the segment where I put the 'asp-action' tag helper.

 

This is my viewmodel called StoreIndexData:

  public class StoreIndexData
  {
public List Stores { get; set; }
public List Departments { get; set; }
  }

This is my Index method where I initialize the models and send it to the view:

 

public async Task Index()
        {
            var viewModel = new StoreIndexData();
            viewModel.Stores = await _context.Stores
                .Include(c => c.StoreChains)
                .Include(d => d.Districts)
                .AsNoTracking().ToListAsync();

            viewModel.Departments = new List();
            viewModel.Departments = (from department in _context.Departments
                              select department).ToList();
            viewModel.Departments.Insert(0, new Department { DepartmentID = 0, DepartmentName = "Select" });
            ViewBag.ListofDepartment = viewModel.Departments;

            return View(viewModel);
        }

Then, in my view, I have this segment to show a dropdownlist for the department class:

="DepartmentName" class="control-label">

                        class="form-control"
                        asp-for="DepartmentID"
                        asp-items="@(new  SelectList(ViewBag.ListofDepartment,"DepartmentID","DepartmentName"))">

  

 When I debug the application, I get the following error:

 

• 'StoreIndexData' does not contain a definition for 'DepartmentName' and no extension method 'DepartmentName' accepting a first argument of type 'StoreIndexData' could be found (are you missing a using directive or an assembly reference?)

  +
  391. #pragma warning restore 1998

• 'StoreIndexData' does not contain a definition for 'DepartmentID' and no extension method 'DepartmentID' accepting a first argument of type 'StoreIndexData' could be found (are you missing a using directive or an assembly reference?)

  +
  391. #pragma warning restore 1998

 

So, which would be the correct way to use the tag helpers in this case?

 

I tried to debug the application deleting the asp-for tag helper and it runs as expected, but I don't believe this is the right thing to do. Any explanation on why is it important to use this tag helper?

 

Thanks! 

 

 _EDIT:

 

Ok, so first, since I'm using a ViewModel, I would need to access the model that contains this property, which is Department, like this:

 

for="Departments.DepartmentName" class="control-label">

BUT, I don't have a singular Department, so, If i changed the ViewModel like this: 

  public class StoreIndexData
  {
public List<Store> Stores { get; set; }
public List<Department> Departments { get; set; }
public string DepartmentName { get; set; }
public int DepartmentID { get; set; }
  }

and change the view back to this: 

<label asp-for="DepartmentName" class="control-label"></label>
                <select
                        class="form-control"
                        asp-for="DepartmentID"
                        asp-items="@(new  SelectList(ViewBag.ListofDepartment,"DepartmentID","DepartmentName"))"></select>

 It works, but I'm not sure if this is the correct procedure.