從列表行爲創建實例

Question

我有一個行爲來支持列表框中的selectedItems。這裏是代碼的一部分。 有沒有一種方法，如果目標又名AssociatedObject.SelectedItems爲空來創建它的一個實例？所有我嘗試失敗...

void ContextSelectedItems_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e) 
{ 
    //Need to unsubscribe from the events so we don't override the transfer 
    UnsubscribeFromEvents(); 
       
    //Move items from the selected items list to the list box selection 
    Transfer(SelectedItems as IList, AssociatedObject.SelectedItems); 
       
    //subscribe to the events again so we know when changes are made 
    SubscribeToEvents(); 
} 

public static void Transfer(IList source, IList target) 
{ 
    if (source == null || target == null) 
    { 
     return; 
    } 
       
    target.Clear(); 
       
    foreach (var o in source) 
    { 
     target.Add(o); 
    } 
} 

UPDATE

這裏是我的代碼的來源。 http://blog.bdcsoft.com/developer-blog/2011/no-binding-for-you-a-listbox-selecteditems-behavior-solution/

Answer 1

不能賦值給一個列表框的selectedItems屬性，因爲它是一個只讀屬性：http://msdn.microsoft.com/en-us/library/system.windows.controls.listbox.selecteditems(v=vs.110).aspx

[BindableAttribute(true)] 
public IList SelectedItems { get; } 

對於使用SetSelectedItems方法。

另外，SelectedItems屬性不應該在ListBox上爲null，而應該是一個空列表。

Answer 2

這可能比您現在認爲mathieu說爲什麼您的代碼不起作用更容易。嘗試像下面的代碼。

HTH，
Berryl

void ContextSelectedItems_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e) 
{ 
//Need to unsubscribe from the events so we don't override the transfer 
UnsubscribeFromEvents(); 

//Move items from the selected items list to the list box selection 
Transfer(SelectedItems as IList, AssociatedObject); 

//subscribe to the events again so we know when changes are made 
SubscribeToEvents(); 
} 

public static void Transfer(IList source, ListBox lb) 
{ 
    if (source == null || lb== null || !lb.SelectedItems.Any()) 
     return; 
} 
lb.SetSelectedItems(source) 
}