MVVM WPF ObservableCollection：錯誤addign項目，ItemsSource綁定

Question

我遇到麻煩，將項目添加到ObservableCollection時使用ItemsSource列表框。我在我的viewmodels構造函數中添加了用於測試的虛擬數據。

我的視圖模型：

public class KabaDeviceListViewModel : KabaBase 
{ 

    private ObservableCollection<KabaDeviceDetailViewModel> _details; 

    public ObservableCollection<KabaDeviceDetailViewModel> KabaDevices 
    { 
     get { return _details; } 
     set 
     { 
      if (value != _details) 
      { 
       _details = value; 
       OnPropertyChanged("KabaDevices"); 
      } 
     } 
    } 


    public KabaDeviceListViewModel() 
    { 

     ObservableCollection<KabaDeviceDetailViewModel> _details = new ObservableCollection<KabaDeviceDetailViewModel>(); 

     KabaDevice kd1 = new KabaDevice("localhost A", "127.0.0.1", true); 
     KabaDeviceDetailViewModel dvm = new KabaDeviceDetailViewModel(kd1); 
     _details.Add(dvm); 

     KabaDevice kd2 = new KabaDevice("localhost B", "127.0.0.1", true); 
     KabaDeviceDetailViewModel dvm2 = new KabaDeviceDetailViewModel(kd2); 
     _details.Add(dvm2); 

     this.KabaDevices = _details; 
    } 
} 

到目前爲止好，但在XAML代碼在這裏出現錯誤，在列表框的ItemsSource的。我不明白我做錯了什麼。我使用VS2010和.NET 4.0。

<UserControl x:Class="KabaTest.View.KabaDeviceListView" 
     ... 
     xmlns:myViewModels="clr-namespace:KabaTest.ViewModel" 
     xmlns:myViews="clr-namespace:KabaTest.View"> 
<UserControl.DataContext> 
    <myViewModels:KabaDeviceListViewModel/> 
</UserControl.DataContext> 
<Grid> 
    <ListBox Margin="5" 
      ItemsSource="{Binding Path=KabaDevices, Mode=TwoWay}" > 
      ScrollViewer.HorizontalScrollBarVisibility="Disabled" > 
     <ListBox.ItemsPanel> 
      <ItemsPanelTemplate> 
       <WrapPanel IsItemsHost="True" Orientation="Horizontal" /> 
      </ItemsPanelTemplate> 
     </ListBox.ItemsPanel> 
     <ListBox.ItemTemplate> 
      <DataTemplate DataType="{x:Type myViewModels:KabaDeviceDetailViewModel}" > 
       <myViews:KabaDeviceDetailView DataContext="{Binding }"/> 
      </DataTemplate> 
     </ListBox.ItemTemplate> 
    </ListBox> 
</Grid> 

在的ItemsSource設置InnerException是：{ 「操作是無效的，同時的ItemsSource正在使用中訪問和修改元素與ItemsControl.ItemsSource了吧。」}。謝謝你的幫助！

Answer 1

您的構造函數可能存在問題。您將支持字段_details分配給該支持字段KabaDevices的公共屬性。不能100％確定這是否是例外的原因，但據我所知，其他一切都應該正常工作。試試這個：

public KabaDeviceListViewModel() 
{ 

    var details = new ObservableCollection<KabaDeviceDetailViewModel>(); 

    KabaDevice kd1 = new KabaDevice("localhost A", "127.0.0.1", true); 
    KabaDeviceDetailViewModel dvm = new KabaDeviceDetailViewModel(kd1); 
    details.Add(dvm); 

    KabaDevice kd2 = new KabaDevice("localhost B", "127.0.0.1", true); 
    KabaDeviceDetailViewModel dvm2 = new KabaDeviceDetailViewModel(kd2); 
    details.Add(dvm2); 

    this.KabaDevices = details; 
}