Result of LINQ Query in MVC SelectList as Value and Text - not working

Stefan Piskorski picture Stefan Piskorski · Feb 21, 2014 · Viewed 36.7k times · Source

I am trying to use the result of a LINQ Query to populate a SelectList in a MVC 5 application. The LINQ query returns customer IDs.

Model

public partial class Pricelist
{
    public int CustomerID { get; set; }
    public int SelectedCustomer { get; set; }

    public Pricelist(int customerID, int selectedCustomer)
    {

    }
}

View

@Html.DropDownList("custList")

Controller (1)

var query = ((from s in db.Pricelists
                     select s.CustId).Distinct()).ToList();

int i = 1;
List<Pricelist> CustomerList = new List<Pricelist>();
foreach (var c in query)
{
    int cust = c;
    Pricelist p = new Pricelist(i, cust);
    CustomerList.Add(p);
    i++;
}

SelectList custList = new SelectList(CustomerList); 
ViewBag.custList = custList;

return View(); 

Which returns a drop down populated with the Model class name (I get an exception if I try to return i and cust .ToString() in the foreach.) I tried this because the Controller method below produced the list of distinct CustomerIDs, but returned NULL when it was POSTed (I think because there was no Value specified in the SelectList)

public ActionResult Create()
{
    var query = (from s in db.Pricelists
                 select s.CustId).Distinct(); 

    SelectList CustomerList = new SelectList(query);

    ViewBag.custList = CustomerList;

    return View();
}

Pointers to where I am going wrong, and how to proceed much appreciated.

Answer

Chris Pratt picture Chris Pratt · Feb 21, 2014

The easiest method is to let Razor worry about the SelectList and just feed it an IEnumerable<SelectListItem>.

ViewBag.custList = CustomerList.Select(m => new SelectListItem { Value = m.Id, Text = m.Name });

Then in your view:

@Html.DropDownListFor(m => m.SomeField, (IEnumerable<SelectListItem>)ViewBag.custList)

You can make that nicer by using a view model that you can strongly type instead of ViewBag. You should really avoid ViewBag as much as possible.