如何在绑定中将 TargetNullValue 设置为文件夹路径?

How to set TargetNullValue as folderpath in binding?

<TextBox Grid.Column="2"  Height="25"   IsReadOnly="True" TextAlignment="Right"  Text="{Binding ElementName=Mygroups, TargetNullValue= 'C:\myfolder1\mysubfolder1',Path=DataContext.FoldernameWithPath,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"  />
<Button Grid.Column="3" Grid.Row="1"  Content="Browse"    Height="25" VerticalAlignment="Bottom"   MinWidth="47"   Command="{Binding ElementName=Mygroups,Path=DataContext.OpenFolderCommand}" CommandParameter="{Binding}" />

在用户点击浏览按钮之前,我需要将文本框绑定到中提到的默认文件夹路径]TargetNullValue。但在我的例子中,它是这样绑定的 C:myfolder1mysubfolder1

我应该怎么做才能像 C:\myfolder1\mysubfolder1 这样绑定文本框?

我不知道是什么原因,但添加另一个 '\' 似乎有效:

<TextBox Grid.Column="2"  Height="25"   IsReadOnly="True" TextAlignment="Right"  Text="{Binding ElementName=Mygroups, TargetNullValue= 'C:\myfolder1\mysubfolder1',Path=DataContext.FoldernameWithPath,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"  />
<Button Grid.Column="3" Grid.Row="1"  Content="Browse"    Height="25" VerticalAlignment="Bottom"   MinWidth="47"   Command="{Binding ElementName=Mygroups,Path=DataContext.OpenFolderCommand}" CommandParameter="{Binding}" />