默认值不能是“Unset”
默认值不能是“Unset”
提问于 2015-07-09 04:45:15
我有一个附加属性，当我将它附加到xaml元素时，我得到一个名为的异常“默认值不能'Unset'"
我的附加属性逻辑
public static DataTemplate GetFooterContentTemplate(DependencyObject obj)
{
return (DataTemplate)obj.GetValue(FooterContentTemplateProperty);
}
public static void SetFooterContentTemplate(DependencyObject obj, DataTemplate value)
{
obj.SetValue(FooterContentTemplateProperty, value);
}
// Using a DependencyProperty as the backing store for GetFooterContentTemplate. This enables animation, styling, binding, etc...
public static readonly DependencyProperty FooterContentTemplateProperty =
DependencyProperty.Register("FooterContentTemplate", typeof(DataTemplate), typeof(RadWindowFooterProperties), new PropertyMetadata(DependencyProperty.UnsetValue));
public static Object GetFooterContent(DependencyObject obj)
{
return (Object)obj.GetValue(FooterContentProperty);
}
public static void SetFooterContent(DependencyObject obj, Object value)
{
obj.SetValue(FooterContentProperty, value);
}
// Using a DependencyProperty as the backing store for RadWindowFooterContent. This enables animation, styling, binding, etc...
public static readonly DependencyProperty FooterContentProperty =
DependencyProperty.RegisterAttached("FooterContent", typeof(Object), typeof(RadWindowFooterProperties), new PropertyMetadata(DependencyProperty.UnsetValue));我的XAML：
<Grid x:Name="FooterRoot" Grid.Row="2" MinHeight="42">
<Border Background="{StaticResource ShellFooterBrush}"/>
<Border Background="{DynamicResource ShellTileBrush}"/>
<ContentPresenter Content="{Binding Path=(Local:RadWindowFooterProperties.FooterContent),RelativeSource={RelativeSource Mode=TemplatedParent}}" ContentTemplate="{Binding Path=(Local:RadWindowFooterProperties.FooterContentTemplate),RelativeSource={RelativeSource Mode=TemplatedParent}}" RecognizesAccessKey="True"/>
</Grid>请让我知道我在哪里做错了。
回答 2
Stack Overflow用户
回答已采纳
发布于 2015-07-09 06:18:41
DependencyProperty.UnsetValue不是依赖项属性的有效默认值。除非要指定null以外的默认值，否则根本不需要注册属性元数据。
您还必须更改FooterContentTemplateProperty的声明，以使用RegisterAttached而不是Register
public static readonly DependencyProperty FooterContentTemplateProperty =
DependencyProperty.RegisterAttached(
"FooterContentTemplate", typeof(DataTemplate), typeof(RadWindowFooterProperties));
public static readonly DependencyProperty FooterContentProperty =
DependencyProperty.RegisterAttached(
"FooterContent", typeof(Object), typeof(RadWindowFooterProperties));Stack Overflow用户
发布于 2015-07-09 04:53:07
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/31308304
复制相关文章
相似问题
腾讯云开发者
