WPF在绑定失败时应用触发器 [英] WPF Applying a trigger on binding failure

问题描述

以下是这一个的问题。

我绑定到异构的对象集合，并非所有对象都具有相同的属性集。我在一个datagrid中这样做。如果绑定失败，我想灰色单元格。如果绑定失败，是否有办法应用触发器？

I am binding to a heterogeneous collection of objects, not all objects have the same set of properties. I am doing this in a datagrid. I would like to gray out the cell if the binding fails. Is there a way to apply a trigger if a binding fails?

编辑：下面的答案适合我的目的，但是我跟着这个问题，因为我想知道如何做（以非黑客的方式 - 我真的爱黑客但是，不要误会我）

The answer below was suitable for my purposes, but i followed up with this question because I would like to know how to do it (in a non hack fashion - i do love the hack however, don't get me wrong)

推荐答案

据我所知，你不能直接做到这一点。但是，如果您可以识别一个永远不会从成功绑定返回的值，则可以创建一个DataTrigger，其绑定具有该值作为其FallbackValue，并触发相同的值：

As far as I know, you can't do this directly. However, if you can identify a value that will never be returned from successful bindings, you can create a DataTrigger whose binding has that value as its FallbackValue, and trigger on that same value:

<!-- Hibble returns only positive values -->
<DataTrigger Binding="{Binding Hibble, FallbackValue=-1}" Value="-1">
  <Setter Property="Background" Value="Red" />
</DataTrigger>

理论上可能会省略FallbackValue并在 {x ：Static DependencyProperty.UnsetValue} ，这将会更加清晰，但这在实践中似乎不起作用。

In theory it might be possible to omit the FallbackValue and trigger on {x:Static DependencyProperty.UnsetValue}, which would be much cleaner, but this doesn't appear to work in practice.

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