Change Cell Format of a WPF Gridcell based on the Value of an other Cell Value

Question

I am starting to get involved with WPF MVVM. Now in a grid I need to format the appearance of a cell based on the value in another cell.

Current Grid Example 1

The values in 'SAP No.' should appear red if the value 'DoppelSAPOrder' is true in the viewmodel. The value 'DoppelSAPOrder' is not displayed in the grid.

The grid is on a UserControl

<UserControl...

    <UserControl.DataContext>
    <model:MainVM />
</UserControl.DataContext>

<Grid>
    <datagrid:ThemedDataGrid HorizontalAlignment="Stretch" Height="auto" VerticalAlignment="Stretch" Width="auto"
                             x:Name="DataGrid" ItemsSource="{Binding Tickets}" AutoGenerateColumns="False"
                             IsReadOnly="True"
                             ClipboardCopyMode="IncludeHeader" SelectedItem="{Binding SelectedTicket}"...

<datagrid:ThemedDataGrid.Columns>

            <datagrid:ThemedDataGrid.Columns>
            <DataGridTextColumn Binding="{Binding CrmTicketId}" Header="Ticket Nr." Width="90">
                <DataGridTextColumn.ElementStyle>
                    <Style TargetType="{x:Type TextBlock}">
                        <Setter Property="HorizontalAlignment" Value="Center" />
                    </Style>
                </DataGridTextColumn.ElementStyle>
            </DataGridTextColumn>

            <DataGridTextColumn Binding="{Binding SapAuftrag}" Header="SAP Nr." Width="85">
                <DataGridTextColumn.ElementStyle>
                    <Style TargetType="{x:Type TextBlock}">
                        <Setter Property="HorizontalAlignment" Value="Center" />
                        <Setter Property="Foreground" Value="{Binding ???, Converter={StaticResource SomeBoolToBrushConverter-ToDo}}"/>
                    </Style>
                </DataGridTextColumn.ElementStyle>
            </DataGridTextColumn>

The grid is bound to a List.

public class SimpleTicketDTO : BaseDTO
{
    public string Kategorie       { get; set; }
    public string Status          { get; set; }
    public string PersonFirmaName { get; set; }
    public bool   HatSAPOrder     { get; set; }
    public string SapAuftrag      { get; set; }
    public bool   DoppelSAPOrder { get; set; }

...

I cannot now access the property 'DoppelSAPOrder ' of the Row in the ElementStyle :-/

Can someone show me how to address this problem?

Answer 1

You want to bind TextBlock property in element style to its' parent row binded object and it can be achieved with the RelativeSource property of the binding like this:

<DataGridTextColumn Binding="{Binding SapAuftrag}" Header="SAP Nr." Width="85">
    <DataGridTextColumn.ElementStyle>
        <Style TargetType="{x:Type TextBlock}">
           <Setter Property="HorizontalAlignment" Value="Center" />
           <Setter Property="Foreground" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}, Path =Item.DoppelSAPOrder,Converter={StaticResource IsObsoleteToTextDecorationsConverter}}"/>
        </Style>
    </DataGridTextColumn.ElementStyle>
</DataGridTextColumn>