How to set DataGridTextColumn text color?

Question

I'm trying to change the color of a DataGridTextColumn.

Here's what I'm doing:

<DataGridTextColumn 
    Header="Status" 
    Binding="{Binding IsActive, 
               Converter= {StaticResource BoolToStatusConverter}}"
    Foreground="{Binding Path=IsActive,
               Converter={StaticResource BoolToColorConverter}}"/>

Text is set properly, but the color won't change, and I'm getting following error:

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or 
FrameworkContentElement for target element. BindingExpression:Path=IsActive; 
DataItem=null; target element is 'DataGridTextColumn' (HashCode=40349079); target 
property is 'Foreground' (type 'Brush')

What should I do for this to work?

Answer 1

You need to specify a Style with a DataTrigger for the column's CellStyle. e.g.

<Page.Resources>
    <Style TargetType="DataGridCell" x:Key="ActiveCellStyle">
        <Setter Property="Foreground" Value="Blue"/>
        <Style.Triggers>
            <DataTrigger Binding="{Binding IsActive}" Value="{x:Null}">
                <Setter Property="Foreground" Value="Green"/>
            </DataTrigger>
            <DataTrigger Binding="{Binding IsActive}" Value="True">
                <Setter Property="Foreground" Value="Red"/>
            </DataTrigger>
        </Style.Triggers>
    </Style>
    <Converters:BoolToTextConverter 
        x:Key="BoolToStatusConverter" 
        TargetCondition="True" 
        IsMatchValue="It's active" 
        IsNotMatchValue="It's dead" />
</Page.Resources>
<Grid>
    <DataGrid ItemsSource="{Binding Items}" AutoGenerateColumns="False">
        <DataGrid.Columns>
            <DataGridTextColumn 
                Header="Status" 
                Binding="{Binding IsActive, 
                    Converter={StaticResource BoolToStatusConverter}}" 
                CellStyle="{StaticResource ActiveCellStyle}"/>
        </DataGrid.Columns>
    </DataGrid>
</Grid>

Answer 2

While not technically a DataGridTextColumn, this is what I usually do:

<DataGridTemplateColumn Header="Status" SortMemberPath="Status">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Status}" Foreground="{Binding Status, Converter={StaticResource StatusToSolidColor}}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

I get the datacontext that I want, and I can resuse converters that I may already have in place in the rest of the application. Futhermore, I don't have to hard code / maintain an extra set of styles and data triggers to get the desired effect.