如何隐藏控制如果底层的DataContext为空？ [英] How to hide a control if the underlying DataContext is null?

问题描述

我在我的视图模型的对象，有一堆的属性，其中一些偶尔会为空。我不想只是显示一些控件，如果这些特殊的控制是空。我怎么会去隐藏控件，如果绑定为空？我在想一些变频器，但不知道我怎么会去究竟这样做。任何想法？

I have an object in my view model that has a bunch of properties, some of them will occasionally be null. I don't want to just show some controls if these particular controls are null. How would I go about hiding the control if the bind is null? I was thinking of some sort of converter, but don't know how I'd go about doing it exactly. Any ideas?

编辑：对不起，我要指出，这也将是在Silverlight，所以我不知道，如果样式触发器会工作......

edit: sorry, I should mention that this will also be in Silverlight, so I'm not sure if Style triggers would work...?

推荐答案

有一个转换器像如下，

public sealed class NullToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value == null ? Visibility.Hidden: Visibility.Visible;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

现在，随着能见度属性的属性绑定为好。就像，

Now, bind the property with the Visibility property as well. Like,

<ListBox ItemsSource="{Binding Path=Squad}" 
         Visibility="{Binding Converter={StaticResource nullToVisibilityConverter}, 
                              Path=Squad}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <CheckBox Content="{Binding}" />
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

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