我工作的一个WPF项目，我创造了一些款式，其中之一是 DataGridCell 的风格，它工作正常。

I am working on a WPF project, and I am creating some styles, one of them is the DataGridCell style, it works fine.

我的问题是：：当用户删除任何行，许多错误显示在Visual Studio的输出窗口

这是错误：

System.Windows.Data Warning: 4 : Cannot find source for binding with reference 
 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.DataGrid', 
 AncestorLevel='1''.
 BindingExpression:Path=CanUserAddRows; DataItem=null; target element is 'DataGridCell' 
 (Name=''); target property is 'NoTarget' (type 'Object')

所以，我想这个错误是因为当 DataGridCell 从的DataGrid 删除，绑定不找到了父母，但是，我能做些什么，以避免这些错误？我的意思是，我怎么能建立一个条件，结合??

So, I guess the error is because when the DataGridCell is removed from the DataGrid, the binding does not find the the Parent, but, What can I do to avoid getting these errors?? I mean, how can I establish a condition for the binding??

我的XAML样式code是如下：

My XAML Style code is as following:

<DataGrid Margin="6,25,6,35" x:Name="dataGrid">            
        <DataGrid.CellStyle>
            <Style TargetType="{x:Type DataGridCell}">
                <Style.Triggers>
                    <MultiDataTrigger>
                        <MultiDataTrigger.Conditions>
                            <Condition Binding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}, Path=CanUserAddRows}" Value="False" />
                            <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="True" />
                        </MultiDataTrigger.Conditions>
                        <Setter Property="Background" Value="#A4A4A4"/>
                    </MultiDataTrigger>
. . . . . 

希望有人能帮助我，在此先感谢。

Hope someone can help me, thanks in advance.

推荐答案

我也遇到这类问题，并设定的 TargetNullValue 和的 FallbackValue 摆脱大部分时间这些绑定错误的。

I have also faced these kind of problems and setting TargetNullValue and FallbackValue gets rid of these binding errors most of the time.

<MultiDataTrigger.Conditions> 
   <Condition Binding="{Binding RelativeSource={RelativeSource FindAncestor, 
                         AncestorType= {x:Type DataGrid}}, Path=CanUserAddRows, 
                         TargetNullValue=False, FallbackValue=False}" Value="False" /> 
   <Condition Binding="{Binding RelativeSource={RelativeSource Self}, 
                         Path=IsSelected, TargetNullValue=False, 
                         FallbackValue=False}" Value="True" /> 
</MultiDataTrigger.Conditions> 

在一般我也试着尽量少用的RelativeSource 尽可能使用的DataContext 在可能的情况。

In general I also try to minimize the use of RelativeSource as much as possible, use DataContext wherever possible.