Question

I’m trying to style the DataGrid to show the red error border when there are no items in it’s ItemsSource collection. I already have all the code written and working for the Triggers.

Here is what I tried:

<Style x:Key="WarningDataGrid" TargetType="DataGrid" BasedOn="{StaticResource {x:Type DataGrid}}">
    <Style.Triggers>
        <Trigger Property="ocean:DataGridBehavior.HasWarning" Value="true">
            <Setter Property="Control.Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Border BorderThickness="1" BorderBrush="Red">
                            <AdornedElementPlaceholder />
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(ocean:CheckBoxBehavior.Warning)}" />
        </Trigger>
    </Style.Triggers>
</Style>

But since I’m not using the validation framework all that happens is the red border replaces the DataGrid.

Do I need to start with the default style? If so where do I find it.

Answer 1

You are replacing the whole template. Just set the BorderBrush :

<Style x:Key="WarningDataGrid" TargetType="DataGrid" BasedOn="{StaticResource {x:Type DataGrid}}">
    <Style.Triggers>
        <Trigger Property="ocean:DataGridBehavior.HasWarning" Value="true">
             <Setter Property="BorderBrush" Value="AliceBlue"/>
            <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(ocean:CheckBoxBehavior.Warning)}" />
        </Trigger>
    </Style.Triggers>
</Style>