InvokeCommandAction not calling

Question

I have a combobox and I need a command in my view model to bind to its ContextMenuOpening event. I've tried referencing System.Windows.Interactivity and using InvokeCommandAction, but the command is not calling. Does anyone see where I'm going wrong?

<ComboBox x:Name="comboBoxAs" Grid.Column="0" VerticalAlignment="Top" Margin="928,62,0,0" Height="25"
            ItemsSource="{Binding Source={StaticResource sas}}"
            SelectedItem="{Binding Path=as, UpdateSourceTrigger=PropertyChanged}"
            Style="{StaticResource ComboBoxDefault}" HorizontalAlignment="Left" Width="212"   >

    <i:Interaction.Triggers>
        <i:EventTrigger EventName="ContextMenuOpening">      

            <i:InvokeCommandAction Command="{Binding ContextMenuOpeningCommand, Mode=OneWay}" />

        </i:EventTrigger>
    </i:Interaction.Triggers>
</ComboBox>

ViewModel:

public ICommand ContextMenuOpeningCommand
{
    get
    {
        if (_contextMenuOpeningCommand == null)
        {
            _contextMenuOpeningCommand = new RelayCommand<object>(param => this.ContextMenuOpening(),
                null);
        }

        return _contextMenuOpeningCommand;
    }
}

public void ContextMenuOpening()
{
    System.Windows.MessageBox.Show("test", "test");
}

private ICommand _contextMenuOpeningCommand;

Answer 1

Please try DropDownOpened to see whether the command gets hit. I tried it and it works here. Hope this helps :)