Adding EventTrigger on a ListView inside DataTemplate results in XamlParseException

Question

I'm creating a WPF app using MVVMLight. I defined a ListView inside a TabControl DataTemplate, like so:

<TabControl.ContentTemplate>
    <DataTemplate>
        <ListView ItemsSource="{Binding Builds}"
            ScrollViewer.HorizontalScrollBarVisibility="Disabled"
            SelectedItem="{Binding SelectedBuild,
                                    Mode=TwoWay}"
            SelectionMode="Single">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="MouseDoubleClick">
                    <i:InvokeCommandAction Command="{Binding BuildSelectedCommand}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </ListView>
    </DataTemplate>
</TabControl.ContentTemplate>

but XAML Designer returns this error (preventing the load of the designer preview):

XamlObjectWriterException: Collection property 'System.Windows.Controls.ListView'.'Triggers' is null.
at System.Xaml.XamlObjectWriter.WriteGetObject()
at System.Xaml.XamlWriter.WriteNode(XamlReader reader)
at System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlReader templateReader, XamlObjectWriter currentWriter)

my Command is defined like so in my ViewModel:

 private RelayCommand _buildSelectedCommand;
 public RelayCommand BuildSelectedCommand => _buildSelectedCommand ??
        (_buildSelectedCommand = new RelayCommand(BuildSelectedAction));

This is the first time I'm seeing this error, and it's happening only at design time, building and runtime it's fine. Removing the i:Interaction.Triggers fix the problem, but I need the DoubleClick event on the list.

If you ask why I didn't add the trigger at the ListItem level, it's because I have to set a property on the ViewModel binding the TabControl Datatemplate, not the ListItem ViewModel.

Thanks a lot for the help!

Luca Spolidoro MSFT Luca Spolidoro MSFT · Accepted Answer · 2016-11-18T00:59:19

2

votes

I just verified that this is a Visual Studio 2015 bug, it doesn't repro in Visual Studio 2017 RC.

Adding EventTrigger on a ListView inside DataTemplate results in XamlParseException

1 Answers