Dropdownlistfor selected values do not persist

Question

I am using Asp.net C# with mvc 4 and in my View I have a Dropdownlistfor, with a class I used of bootstrap-multiselect, as in the image:

And the code in the view:

@Html.DropDownListFor(m => m.Estagios, (IEnumerable<SelectListItem>)Model.Estagios, new { @class = "multiselect form-control", multiple = "multiple" })

When I do the search, I do a Post in a method in the Controller and within that method (both get and post) feed the Viewmodel and the Selectlist:

So, he’s taking the values I posted, which are 1, 3 and 5. I give a Return View passing to Viewmodel. When he posts and the page reloads, he assumes the value in the right querystring and does all the processing of the right search as programmed, but he does not assume the values selector in Dropdownlist, bringing only the first of the list:

I’m doing something wrong?

The plugin used for css/javascript is this: davidstutz.github.io/bootstrap-multiselect

Answer 1

I don’t know if this way of yours works with Multiselect.

Do it like this, your HTML will be a Listbox and not a Dropdownlistfot

 @Html.ListBox("Estagios", null, new { @class = "multiselect-group-clickable" })

Your script will be

   <script language="javascript">
$(document).ready(function () {

    $('#Estagios').multiselect({
        includeSelectAllOption: true,
        maxHeight: 200
    });

});
</script>

And your controller will not call a Selectlist but a Multiselect

ViewBag.Estagios = new MultiSelectList(_estagioService.ListarEstagios(), "EstagioId", "Nome", estagios);

Check the variable names to test..

Answer 2

    //Você deve usar um MultiSelectList:
    ViewBag.itens = MultiSelectList(itens, "id", "Nome", itensSelected);


//E no html:
@Html.DropDownListFor(model => model.Estagios, (SelectList)ViewBag.itens, "Selecione")