Question

I have TWO custom controls. First I have an checkbox custom control, myCheckboxControl, (simplied xaml below)

<UserControl x:Class="UserControls.myCheckboxControl"><Grid>
        <CheckBox x:Name="chkboxList" HorizontalAlignment="Center" Checked="chkboxList_Checked">
</Grid></UserControl>

I also have a a custom DataGrid control (simplified xaml below) that contains the checkbox control in a DataTemplate

<UserControlx:Class="UserControls.myDataGridControl"><DataGrid x:Name="dgMyGrid>
<DataGrid.Columns>
          <DataGridTemplateColumn x:Name="tempCol" Header="Checkbox(L)">
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <localControls:myCheckboxControl x:Name="controlList"/>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
        </DataGrid.Columns>
    </DataGrid>

Then I have the DataGrid (myDataGridControl) in my MainWindow.

The question I have is that I have a Button on the MainWindow. When that Button is Clicked, I need it to also check the checkbox within myCheckboxControl. I can get the SelectedItem of the datagrid, but just not sure how to get my 2 level deep checkbox to get checked.

Thanks in advance.

Answer 1

As you have already known that the checkbox is a descendent of a user control which is hosted on a datagrid row.

So you will have to resolve these 2 level boundaries by using a mediator property at myCheckboxControl to hold CheckBox.IsChecked. You can introduce a new dependency property in myCheckboxControl say IsCheckBoxChecked an use that in further discussion.

I am using another property called Tag which is a placeholder for any extra information one may want to add against a framework element.

    <UserControl x:Class="UserControls.myCheckboxControl">
        <Grid>
            <CheckBox x:Name="chkboxList"
                      HorizontalAlignment="Center"
                      IsChecked="{Binding
                                    Tag,
                                    RelativeSource={RelativeSource
                                        AncestorType={x:Type UserControl}}
                                    Mode=TwoWay}">
       </Grid>
   </UserControl>


   <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <localControls:myCheckboxControl
                       Tag="{Binding
                                IsSelected,
                                Mode=TwoWay,
                                RelativeSource={RelativeSource
                                   AncestorType={x:Type DataGridRow}}}"
                       x:Name="controlList"/>
        </DataTemplate>
   </DataGridTemplateColumn.CellTemplate>  

Thus when you programmatically select datagrid row(s) then corresponding checkbox on that row will get checked. Also when you check the checkbox the row will get selected and vice versa.

Now if you dont want selection to take place upon checking the checkbox, you will have to introduce a INotifyPropertyChanged based notifiable property at row item level.

E.g. if you are binding a list of employees to the datagrid then each employee class must have a settable property called “IsSelected”. This class must implement INotifyPropertyChanged interface and should raise a property changed notification from setter that IsSelected property.

In such case the binding is changed to this…

            <localControls:myCheckboxControl
                       Tag="{Binding
                                IsSelected,
                                Mode=TwoWay}"
                       x:Name="controlList"/>

Let me know if this helps.