How to change style of data grid cell based on conditional operator in WPF

Question

I am working on a wpf application to show record and i need to change style of text in a particular column "Price" if it is lesser than 50. Code is given as below:

 <DataGrid ItemsSource="{Binding Path= Shares}" HorizontalAlignment="Left" Margin="89,201,0,0" CanUserAddRows="False" AutoGenerateColumns="False" VerticalAlignment="Top" Height="280" Width="500">
       <DataGrid.Columns>
            <DataGridTextColumn Header="Company" Binding="{Binding CompanyName}" Width="250" />
            <DataGridTextColumn Header="Share Price" Binding="{Binding Price}" />                       
        </DataGrid.Columns>
    </DataGrid>

So i need to change foreground color of price text if it is < 50.

Can you please suggest how to do it?

Answer 1

You can't do this kind of comparisons in XAML since there is no < operator defined but you could use a converter:

<DataGrid ItemsSource="{Binding Path= Shares}" HorizontalAlignment="Left" Margin="89,201,0,0" CanUserAddRows="False" AutoGenerateColumns="False" 
                  VerticalAlignment="Top" Height="280" Width="500"
                  xmlns:local="clr-namespace:WpfApplication1">
    <DataGrid.Resources>
        <local:MyConverter x:Key="conv" />
    </DataGrid.Resources>
    <DataGrid.Columns>
        <DataGridTextColumn Header="Company" Binding="{Binding CompanyName}" Width="250" />
        <DataGridTextColumn Header="Share Price" Binding="{Binding Price}">
            <DataGridTextColumn.ElementStyle>
                <Style TargetType="TextBlock">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding Price, Converter={StaticResource conv}}" Value="True">
                            <Setter Property="Foreground" Value="Green" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </DataGridTextColumn.ElementStyle>
        </DataGridTextColumn>
    </DataGrid.Columns>
</DataGrid>

---

namespace WpfApplication1
{
    public class MyConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            decimal d = System.Convert.ToDecimal(value);
            return d < 50;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException();
        }
    }
}

The Convert method returns true if the Price property is < 50 and then the Foreground of the TextBlock is changed to Green.