Getting Multiple Selected Values in Html.DropDownlistFor

Question

@Html.DropDownListFor(m => m.branch, CommonMethod.getBranch("",Model.branch), "--Select--", new { @multiple = "multiple" })  @Html.DropDownListFor(m => m.division, CommonMethod.getDivision(Model.branch,Model.division), "--Select--", new { @multiple = "multiple" }) 

I have two instances of DropDownListFor. I want to set selected as true for those which have previously stored values for Model.branch and Model.division. These are string arrays of stored ids

class CommonMethod {     public static List<SelectListItem> getDivision(string [] branchid , string [] selected)     {         DBEntities db = new DBEntities();         List<SelectListItem> division = new List<SelectListItem>();         foreach (var b in branchid)             {                 var bid = Convert.ToByte(b);                 var div = (from d in db.Divisions where d.BranchID == bid select d).ToList();                 foreach (var d in div)                 {                     division.Add(new SelectListItem { Selected = selected.Contains(d.DivisionID.ToString()), Text = d.Description, Value = d.DivisionID.ToString() });                 }             }         }          return division;     } } 

The returned value of division is selected as true for the selected item in the model, but on view side it is not selected.

Answer 1

Use a ListBoxFor instead of DropDownListFor:

@Html.ListBoxFor(m => m.branch, CommonMethod.getBranch("", Model.branch), "--Select--")  @Html.ListBoxFor(m => m.division, CommonMethod.getDivision(Model.branch, Model.division), "--Select--") 

The branch and division properties must obviously be collections that will contain the selected values.

And a full example of the proper way to build a multiple select dropdown using a view model:

public class MyViewModel {     public int[] SelectedValues { get; set; }     public IEnumerable<SelectListItem> Values { get; set; } } 

that would be populated in the controller:

public ActionResult Index() {     var model = new MyViewModel();      // preselect items with values 2 and 4     model.SelectedValues = new[] { 2, 4 };      // the list of available values     model.Values = new[]     {         new SelectListItem { Value = "1", Text = "item 1" },         new SelectListItem { Value = "2", Text = "item 2" },         new SelectListItem { Value = "3", Text = "item 3" },         new SelectListItem { Value = "4", Text = "item 4" },     };      return View(model); } 

and in the view:

@model MyViewModel ... @Html.ListBoxFor(x => x.SelectedValues, Model.Values) 

It is the HTML helper that will automatically preselect the items whose values match those of the SelectedValues property.

Answer 2

For me it works also for @Html.DropDownListFor:

Model:

public class MyViewModel {     public int[] SelectedValues { get; set; }     public IEnumerable<SelectListItem> Values { get; set; } } 

Controller:

public ActionResult Index() {     var model = new MyViewModel();      // the list of available values     model.Values = new[]     {         new SelectListItem { Value = "2", Text = "2", Selected = true },         new SelectListItem { Value = "3", Text = "3", Selected = true },         new SelectListItem { Value = "6", Text = "6", Selected = true }     };      return View(model); } 

Razor:

@Html.DropDownListFor(m => m.SelectedValues, Model.Values, new { multiple = "true" }) 

Submitted SelectedValues in controller looks like: