Sorting a WPF Data Grid Text Column With MultiBinding

Question

Below is a DataGridTextColumn definition from my WPF datagrid with the converter difination and the converter code. Can someone please tech me how to sort this column, I believe I need to use Icomparer but after trying to adapt online example my attempts have failed. If you could give an explanation in VB.Net that would really help - thanks.

<Window.Resources>
    <c:DurationConverter x:Key="MyDurationConverter"/>
    <c:DistanceConverter x:Key="MyDistanceConverter"/>
</Window.Resources>

<DataGridTextColumn Header="Duration" Width="70" x:Name="Duration">
  <DataGridTextColumn.Binding >
     <MultiBinding Converter="{StaticResource MyDurationConverter}">
        <Binding Path="StartDate" />
        <Binding Path="EndDate"/>
        <Binding Mode="OneWay" />
      </MultiBinding>
  </DataGridTextColumn.Binding>
 </DataGridTextColumn>

Friend Class DurationConverter
    Implements IMultiValueConverter

    Friend Function Convert(values() As Object, targetType As System.Type, parameter As Object, culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IMultiValueConverter.Convert
        Return (CType(values(1), DateTime) - CType(values(0), DateTime)).ToString

    End Function

    Friend Function ConvertBack(value As Object, targetTypes() As System.Type, parameter As Object, culture As System.Globalization.CultureInfo) As Object() Implements System.Windows.Data.IMultiValueConverter.ConvertBack
        Throw New NotImplementedException
    End Function
End Class

Answer 1

Since your converter only calculates TimeSpan between EndDate and StartDate, in your case, it will be much easier if you create another public TimeSpan property in your object, lets call it Duration, which will return EndDate - StartDate and bind that directly, without IMultiValueConverter, to your DataGridTextColumn.

<DataGridTextColumn Header="Duration" Width="70" x:Name="Duration" Binding="{Binding Path=Duration}">

For presentation it will be converted ToString() but will still compare it as TimeSpan and you will be able to sort by it like any other column