How to bind DataGrid Sorting event to Prism ViewModel DelegateCommand

Question

How do I bind the sorting command of my datagrid to view model?

Below is my XAML Code

<DataGrid ItemsSource="{Binding ViewModels}"
          CanUserSortColumns="True"
          Sorting="{Binding ViewModel_SortingCommand}">
</DataGrid>

Below is the ViewModel implemented that cause the error in binding

ViewModel_SortingCommand = new DelegateCommand<DataGridSortingEventArgs>(ViewModel_Sorting;

public void ViewModel_Sorting(DataGridSortingEventArgs args)
{
    // Error on binding
}

Answer 1

Since Sorting is an event, you cannot bind it directly, but you can use an EventTrigger.

<DataGrid ItemsSource="{Binding ViewModels}"
          CanUserSortColumns="True">
   <i:Interaction.Triggers>
      <i:EventTrigger EventName="Sorting">
         <i:InvokeCommandAction Command="{Binding ViewModel_SortingCommand}"/>
      </i:EventTrigger>
   </i:Interaction.Triggers>
</DataGrid>

If you use the legacy blend behaviors shipped with Blend, use this namespace:

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"

If you use the new Microsoft.Xaml.Behaviors.Wpf Nuget package, use this namespace:

xmlns:i="http://schemas.microsoft.com/xaml/behaviors"

If you need to process the event args in your command, set PassEventArgsToCommand to True:

<b:InvokeCommandAction Command="{Binding FavContextMenuEditCmd}" PassEventArgsToCommand="True"/>

Also note, that there is an EventArgsParameterPath property to specify a property in the event args that should be passed to the command and an EventArgsConverter property to use a converter. These are useful to avoid passing UI related types like event args to your view model.