过滤 ObservableCollection? [英] Filtering an ObservableCollection?
问题描述
当我将 ListBox 直接绑定到 ObservableCollection 时,我会在我的 ListBox 中获得实时更新,但是一旦我在混合中添加其他 LINQ 方法,我的 ListBox 就不再收到 ObservableCollection 的任何更改通知.
When I bind a ListBox directly to an ObservableCollection I get the real-time updates displayed in my ListBox, but as soon as I add other LINQ methods in the mix my ListBox is no longer notified of any changes to the ObservableCollection.
这里我举个例子;
public partial class MainPage : PhoneApplicationPage
{
ObservableCollection<String> Words = new ObservableCollection<string>();
public MainPage()
{
InitializeComponent();
listBox1.ItemsSource = Words;
}
private void AddButton_Click(object sender, RoutedEventArgs e)
{
Words.Add(DateTime.Now.ToString());
}
}
在这里,我向一个简单的页面添加了一个按钮和一个列表框,单击按钮使新项目立即出现在列表框中.
Here I've added a Button and a ListBox to a simple Page, and clicking the button makes the new item appear immediately in the ListBox.
但是,如果我改变了
listBox1.ItemsSource = Words;
到
listBox1.ItemsSource = Words.Where(w => w.Contains(":"));
ListBox 不再更新.
the ListBox is no longer updated.
如何在我的 ObservableCollection 和 ListBox 之间添加一个过滤器",并且仍然让它更新而无需再次设置 .ItemsSource?
How can I add a "filter" between my ObservableCollection and the ListBox, and still get it to update without having to set the .ItemsSource again?
推荐答案
尝试像这样使用 CollectionViewSource:
Try using the CollectionViewSource like this:
WordsView = new CollectionViewSource();
WordsView.Filter += Words_Filter;
WordsView.Source = Words;
// ...
void Words_Filter(object sender, FilterEventArgs e)
{
if (e.Item != null)
e.Accepted = ((string)e.Item).Contains(":");
}
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