Question

I’m using the MVVM Light Toolkit and I have a DataGrid bound to an ObservableCollection. There is only one text column displayed. I’d like the text of the cell to be Bold or Normal depending on a boolean that is inside the object displayed. I figured I could use RelayCommands but they only take 1 parameter and I need at least 2 to get the CellContent (the DataGridRowEventArgs and the DataGrid itself). I tried to fire a RelayCommand Execute delegate on “LoadingRow” event but with only one parameter I couldn’t do it.

Here is the DataGrid in the XAML:

<DataGrid x:Name="dataGrid1" HorizontalAlignment="Left" Margin="112,34,0,8" Width="100" IsReadOnly="True" CanUserReorderColumns="False" CanUserResizeColumns="False" CanUserSortColumns="False" CanUserResizeRows="False" ItemsSource="{Binding CurrentNewsList}" AutoGenerateColumns="False" SelectedIndex="0">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Title}" MinWidth="92" Width="Auto" FontFamily="Segoe UI" Foreground="Black" FontWeight="{Binding CurrentNewsList[0].MyFont}"/>
        </DataGrid.Columns>
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="SelectionChanged">
                <Custom:EventToCommand Command="{Binding NewsSelectedCommand}" CommandParameter="{Binding SelectedIndex, ElementName=dataGrid1}"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </DataGrid>

I set the grid in Blend. Notice that the FontWeight is bound like “{Binding CurrentNewsList[0].MyFont}”. Is it right ? I also tried “{Binding MyFont}” but both got the same result: No BOld 🙁

MyFont is set in the Object constructor with a boolean:

MyFont = newIsRead ? FontWeights.Normal : FontWeights.Bold;

Please help.

Thx

Answer 1

You could just use an implicit style and a trigger:

<DataGrid.Resources>
    <Style TargetType="DataGridCell">
        <Style.Triggers>
            <DataTrigger Binding="{Binding MyBoolean}" Value="True">
                <Setter Property="TextElement.FontWeight" Value="Bold" />
            </DataTrigger>
        </Style.Triggers>
    </Style>
</DataGrid.Resources>

(If you ever have more columns you could just use the styles on the column (ElementStyle & ElementEditingStyle) instead to limit the effect)