WPF Binding FallbackValue设置为Binding [英] WPF Binding FallbackValue set to Binding

问题描述

我正在尝试这样做：

 < Label Content ={Binding SelectedItem.Name，ElementName = groupTreeView，
 FallbackValue = {Binding RootGroup.Name}}/> 
  

如果任何人有另一个把戏把它拉下来，那将是很棒的。

解决方案

你正在寻找的东西叫PriorityBinding（＃6 on 这个列表）

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（来自文章）

PriorityBinding指向
命名多个数据绑定，顺序为
，最理想的是最不希望的。
这样，如果第一个绑定失败，
为空和/或默认，另一个
绑定可以占用它。

例如

 < TextBox> 
< TextBox.Text> 
< PriorityBinding> 
< Binding Path =LastNameNonExistantIsAsync =True/> 
< Binding Path =FirstNameIsAsync =True/> 
< / PriorityBinding> 
< /TextBox.Text> 
< / TextBox> 
  

Is there a way to have another binding as a fallback value?

I'm trying to do something like this:

<Label Content="{Binding SelectedItem.Name, ElementName=groupTreeView,
                         FallbackValue={Binding RootGroup.Name}}" />

If anyone's got another trick to pull it off, that would be great.

解决方案

What you are looking for is something called PriorityBinding (#6 on this list)

(from the article)

The point to PriorityBinding is to name multiple data bindings in order of most desirable to least desirable. This way if the first binding fails, is empty and/or default, another binding can take it's place.

e.g.

<TextBox>
    <TextBox.Text>
        <PriorityBinding>
            <Binding Path="LastNameNonExistant" IsAsync="True" />
            <Binding Path="FirstName" IsAsync="True" />
        </PriorityBinding>
    </TextBox.Text>
</TextBox>

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