Razor mutliselect dropdown- multiselect dropdownlist with selected values in ASP.NET MVC when page loaded

Question

I need a way to set Database retrieve values in a multi select drop down in a edit view in a web application (ASP.NET, Mvc) (load drop down with selected values when page loaded)

from view code,I passed selected ids in to selected values array.(when I return values from DB , assign those in to a array then assign to here.

I need a edit view by set selecting already selected values.

//View
    <div class="form-group">
    <label>Choose Categories</label>
    @Html.DropDownListFor(model => model.SelectedValues, new MultiSelectList(Models.GetCategoryList().OrderBy(c => c.Value), "Key", "Value"), "Select Category", new { @class = "chzn-select form-control", multiple = "multiple" })                               
    </div>

//Model    
public int[] SelectedValues { get; set; }

//Controller
        public ActionResult Edit(int id)
        {         
            return View(GetDetails(id));
        }

In GetDetails(id) take values from DB , and return a model object

public GetDetails()
{
            int[] arr = new int[2];
            arr[0] = 4;
            arr[1] = 5;
            modelObj.SelectedValues = arr;
.......
......
return modelObj;
}

please anyone suggest way to do this

Thank you.