WPF MVVM: EventTrigger is not working inside CheckBox

Question

I'm building an application with WPF in MVVM style. I'm trying to make filter on my DataGrid when I check or uncheck several CheckBoxes for filtering.

I've found solution with Interaction.Triggers, but it's not working for me in this case.

Here is my code:

<ListBox 
            ItemsSource="{Binding PortsFilterSource}"
            Background="LightGray"
            BorderThickness="0"
            Grid.Column="1">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <CheckBox 
                        Content="{Binding Name}"
                        IsChecked="{Binding IsChecked}">

                        <i:Interaction.Triggers>
                            <i:EventTrigger EventName="Unchecked">
                                <i:InvokeCommandAction Command="{Binding FilterCommand}"/>
                            </i:EventTrigger>
                            <i:EventTrigger EventName="Checked">
                                <i:InvokeCommandAction Command="{Binding FilterCommand}"/>
                            </i:EventTrigger>
                        </i:Interaction.Triggers>
                    </CheckBox>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

Everything is working great except FilterCommand. I have this in my C# code:

public DelegateCommand<object> FilterCommand { get; set; }
...
FilterCommand = new DelegateCommand<object>(Filter);

Filter(object obj) is a function, but it is not entered when I check or uncheck any of my CheckBoxes.

Any help would be very appreciated.

Look at the output window when debugging, do you have any binding errors? — ajg, Aug 01 '17 at 13:17
Oh, yes, I have: System.Windows.Data Error: 40 : `BindingExpression path error: 'FilterCommand' property not found on 'object' ''FilterModel' (HashCode=57774494)'. BindingExpression:Path=FilterCommand; DataItem='FilterModel' (HashCode=57774494); target element is 'InvokeCommandAction' (HashCode=8505800); target property is 'Command' (type 'ICommand')` — francosy, Aug 01 '17 at 13:22
@JanDotNet I have an object `FilterModel` in different file than `Filter` method. It cannot be static. Is there any other way to call it? — francosy, Aug 01 '17 at 13:33
But the `FilterCommand` and the `IsChecked` properties are in the same class, isn't it`? — JanDotNet, Aug 01 '17 at 13:35
@JanDotNet No. I have class `FilterModel` with 2 attributes - `Name` and `IsChecked`. `FilterModel` is `DelegateCommand` in `MainViewModel` — francosy, Aug 01 '17 at 13:40

score 5 · Accepted Answer · answered Aug 01 '17 at 13:45

The problem is, that the data context of the list item is of type FilterModel, but the FilterCommand is in the parent view model.

Try the following binding for the command:

{Binding DataContext.FilterCommand, RelativeSource={RelativeSource AncestorType={x:Type ListBox}}}

score 1 · Answer 2 · answered Jun 21 '22 at 11:24

this is work for me.

<DataGridTemplateColumn  Header="IsApved"  IsReadOnly="False" CanUserSort="False" Width="55">
                    <DataGridTemplateColumn.CellTemplate >
                        <DataTemplate>
                            <CheckBox 
                        Content="{Binding Name}"
                        IsChecked="{Binding IsSelect,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">

                                <i:Interaction.Triggers>
                                    <i:EventTrigger EventName="Unchecked">
                                        <i:InvokeCommandAction Command="{Binding DataContext.CheckCommand,RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/>
                                    </i:EventTrigger>
                                    <i:EventTrigger EventName="Checked">
                                        <i:InvokeCommandAction Command="{Binding DataContext.CheckCommand,RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}"/>
                                    </i:EventTrigger>
                                </i:Interaction.Triggers>
                            </CheckBox>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>

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WPF MVVM: EventTrigger is not working inside CheckBox

2 Answers2

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