MultiSelectList does not make selected selected

Question

我有一個multiselectlist的問題，如果我將dropObjectcategories懸停在調試模式下，它包含4個應該選擇的項目。

List<int> selectedObjectcategoryIDs = new List<int>(); 

foreach (Objectcategory item in bo.Objectcategories) 
{ 
    selectedObjectcategoryIDs.Add(item.ObjectcategoryID); 
} 

MultiSelectList dropObjectcategories = new MultiSelectList(_bs.GetObjectcategories(), "ObjectcategoryID", "ObjectcategoryName", selectedObjectcategoryIDs); 

它仍然獲取呈現不選擇任何像這樣的項目：

<select id="dropObjectcategories" multiple="multiple" name="dropObjectcategories"><option value="3">Airplanes</option><option value="10">Cars</option><option value="8">Computers</option><option value="9">Thingies</option></select> 

什麼可能是錯在這裏？

/M

Answer 1

試着這麼做：

var selectedObjectcategoryIDs = 
    from oc in bo.Objectcategories 
    select oc.ObjectcategoryID; 

MultiSelectList dropObjectcategories = new MultiSelectList(_bs.GetObjectcategories(), "ObjectcategoryID", "ObjectcategoryName", selectedObjectcategoryIDs); 

是否行得通？