我在Window的右侧设置了一个ContentControl,并设置了Content绑定Items(它的类型是ObservableCollection)。现在我想实现它:如果没有项目,ContentControl选择第一个DataTemplate,并将项目添加到项目中,ContentControl将选择第二个DataTemplate来显示一些信息。
像这样:
问题是当我将一项添加到项目中时,ContentControl 没有更新和更改 DataTemplate,我尝试设置模式、UpdateSourceTrigger 等,但失败了。在ViewModel中,删除一个项目后,我使用这个语句,它会工作得很好:
private void ExecuteDeleteClientCommand()
{
...
if (DeleteClient(item))
{
ObservableCollection<MyViewModel> tmp = TabItems;
TabItems = null;
TabItems = tmp;
}
}
.
<ContentControl
ContentTemplateSelector="{StaticResource MyDataTemplateSelector}"
Content="{Binding Items}"/>
.
public class SingleClientDataTemplateSelector : DataTemplateSelector
{
public override DataTemplate SelectTemplate(object item,
DependencyObject container)
{
ObservableCollection<MyViewModel> obj =
item as ObservableCollection<MyViewModel>;
if (null == obj || 0 == obj.Count)
{
return App.Current.FindResource("NullItemDataTemplate") as DataTemplate;
}
return App.Current.FindResource("DefaultDataTemplate") as DataTemplate;
}
}
Edited:使用这种方式删除一项后也失败:
RaisePropertyChanging(ItemsPropertyName);
RaisePropertyChanged(ItemsPropertyName);
但我想知道为什么它可以很好地配合.
Edited2这是声明:
public const string ItemsPropertyName = "Items";
private ObservableCollection<MyViewModel> items = new ObservableCollection<MyViewModel>();
public ObservableCollection<SingleClientDetailViewModel> TabItems
{
get { return items; }
set
{
if (items == value) { return;}
RaisePropertyChanging(ItemsPropertyName);
items = value;
RaisePropertyChanged(ItemsPropertyName);
}
}