DataGridTemplateColumn shows red border for row level validation errors

[eugenelepekhin]

Hi,
I have a datagrid bound to list of items that implement INotifyDataErrorInfo. If there are errors on the entire item any DataGridTemplateColumn shows red box around cells of that column on the erroneous row.
I tried to add style to DataGrid.Resources:

<Style TargetType="ContentPresenter">
	<Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
</Style>

but it still showing red box.
Any suggestions on how to get rid of the red box?

[eugenelepekhin]

Here is an example.
The item class

	public class MyItem : INotifyDataErrorInfo {
		public event EventHandler<DataErrorsChangedEventArgs>? ErrorsChanged;

		public bool HasErrors => true;

		public string? Name { get; set; }
		public int Number { get; set; }

		public IEnumerable GetErrors(string? propertyName) {
			if(string.IsNullOrEmpty(propertyName)) {
				yield return "Error on MyItem: " + this.Name;
			}
		}
	}

the data grid:

		<DataGrid ItemsSource="{Binding Path=Items}" AutoGenerateColumns="False" RowHeaderWidth="30">
			<DataGrid.RowValidationErrorTemplate>
				<ControlTemplate>
					<Grid DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridRow}}}" Background="Transparent" ToolTip="{Binding Path=(Validation.Errors)/ErrorContent}">
						<TextBlock Text="!" FontWeight="Bold" Foreground="Red"/>
					</Grid>
				</ControlTemplate>
			</DataGrid.RowValidationErrorTemplate>

			<DataGrid.Columns>
				<DataGridTextColumn Header="Name" Binding="{Binding Path=Name}"/>
				<DataGridTextColumn Header="Number" Binding="{Binding Path=Number}"/>
				<DataGridTemplateColumn Header="Template">
					<DataGridTemplateColumn.CellTemplate>
						<DataTemplate>
							<Button Content="See red?"/>
						</DataTemplate>
					</DataGridTemplateColumn.CellTemplate>
				</DataGridTemplateColumn>
			</DataGrid.Columns>
		</DataGrid>

[miloush]

Do you have a small repro project people can try?

[eugenelepekhin]

WpfTemplateColumnErrorTest.zip
Here it is

[miloush]

Thanks! You are almost there. You need to set an actual type to the style for it to apply the way you want.

<Style TargetType="{x:Type ContentPresenter}">

[eugenelepekhin]

That is almost works, but oddly enough if I have in the template some bindings it shows the issue again.
Please look at this modification:

		<DataGrid ItemsSource="{Binding Path=Items}" AutoGenerateColumns="False" RowHeaderWidth="30">
			<DataGrid.Resources>
				<Style TargetType="{x:Type ContentPresenter}">
					<Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
				</Style>
			</DataGrid.Resources>
			<DataGrid.RowValidationErrorTemplate>
				<ControlTemplate>
					<Grid DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridRow}}}" Background="Transparent" ToolTip="{Binding Path=(Validation.Errors)/ErrorContent}" MinWidth="20">
						<TextBlock Text="!" FontWeight="Bold" Foreground="Green" HorizontalAlignment="Stretch"/>
					</Grid>
				</ControlTemplate>
			</DataGrid.RowValidationErrorTemplate>

			<DataGrid.Columns>
				<DataGridTextColumn Header="Name" Binding="{Binding Path=Name}"/>
				<DataGridTextColumn Header="Number" Binding="{Binding Path=Number}"/>
				<DataGridTemplateColumn Header="Template">
					<DataGridTemplateColumn.CellTemplate>
						<DataTemplate>
							<!--<Button Content="See red?"/>-->
							<Button Content="See red?" Tag="{Binding Path=.}"/>
						</DataTemplate>
					</DataGridTemplateColumn.CellTemplate>
				</DataGridTemplateColumn>
			</DataGrid.Columns>
		</DataGrid>

If you comment button with Tag and binding and uncomment button without one it works, but with binding it shows red border again.

[miloush]

Right, you need to be distinguishing between errors of the cell and errors of the buttons. If there is no binding on the button, it has no errors, but the cell still does. You can see that easier if you give it some space:

<DataGrid ItemsSource="{Binding Path=Items}" AutoGenerateColumns="False" RowHeaderWidth="30">
    <DataGrid.Resources>
        <!--<Style TargetType="{x:Type ContentPresenter}">
            <Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
        </Style>-->
    </DataGrid.Resources>
    <DataGrid.RowValidationErrorTemplate>
        <ControlTemplate>
            <Grid DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridRow}}}" Background="Transparent" ToolTip="{Binding Path=(Validation.Errors)/ErrorContent}" MinWidth="20">
                <TextBlock Text="!" FontWeight="Bold" Foreground="Green" HorizontalAlignment="Stretch"/>
            </Grid>
        </ControlTemplate>
    </DataGrid.RowValidationErrorTemplate>

    <DataGrid.Columns>
        <DataGridTextColumn Header="Name" Binding="{Binding Path=Name}"/>
        <DataGridTextColumn Header="Number" Binding="{Binding Path=Number}"/>
        <DataGridTemplateColumn Header="Template">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <StackPanel>
                        <Button Content="See red?" Margin="10,0,0,0" />
                        <Button  Content="See red?" Tag="{Binding Path=.}" Margin="0,0,10,0"/>
                    </StackPanel>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

The ContentPresenter is applicable to the cell, but not to the buttons, you would need a style for buttons specifically.

[eugenelepekhin]

Awesome, thanks a lot.