Question

I have recently found out about BindingGroups, and it seem rather nice.
But I can’t get it to work in my ListView that is filled with data represented in DataTemplates.

(In advance I just like to say: sorry for all the code, it’s just to give you a better understanding)

So in XAML it looks something like this:

<StackPanel Name="stpData">
    <StackPanel.BindingGroup>
        <BindingGroup />
    </StackPanel.BindingGroup>

    <!-- This works nice! -->
    <TextBox Text="{Binding Path=name}" />
    <CheckBox IsChecked="{Binding Path=enable}" />

    <!-- This doesn't work so nice... -->
    <ListView Name="lvBools" ItemsSource="{Binding Path=myList}">
        <ListView.View>
            <GridView>
                <GridViewColumn>
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <StackPanel>
                                <CheckBox IsChecked="{Binding bools}" />
                            </StackPanel>
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>
            </GridView>
        </ListView.View>
    </ListView>
</StackPanel>

And code-behind:

public MainWindow()
{
    InitializeComponent();

    TestData Data = new TestData()
    {
        name = "Test",
        enable = true,
        myList = new List<TestData.myItem> 
        {
            new TestData.myItem(true), 
            new TestData.myItem(true), 
            new TestData.myItem(false) 
        },
    };

    stpData.DataContext = Data;
    stpData.BindingGroup.BeginEdit();
}

private void btnSave_Click(object sender, RoutedEventArgs e)
{
    stpData.BindingGroup.CommitEdit();
    stpData.BindingGroup.BeginEdit();
}

private void btnCancel_Click(object sender, RoutedEventArgs e)
{
    stpData.BindingGroup.CancelEdit();
    stpData.BindingGroup.BeginEdit();
}

public class TestData
{
    public class myItem
    {
        public myItem(bool b)
        {
            this.bools = b;
        }
        public bool bools { get; set; }
    }

    public string name { get; set; }
    public bool enable { get; set; }
    public List<myItem> myList { get; set; }
}

So what happends it that when I change the name, or press the enable CheckBox, those changes won’t be submitted until I press the SaveButton (btnSave_Click) (not included in the XAML )
Or if I press a Cancel button changes is “restored”.
But if I click one of the checkBoxes in the ListView, those changes will be submitted immediately.

My own guess: The ListView (or maybe even the StackPanel in the DataTemplate) stops the BindingGroup inheritance chain. But in that case, how can I include them?

EDIT
I have also tried to add a new BindingGroup to the DataTemplate:

<DataTemplate>
    <StackPanel x:Name="SPpan">
        <StackPanel.BindingGroup>
            <BindingGroup Name="BGStackPanel" />
        </StackPanel.BindingGroup>
        <CheckBox IsChecked="{Binding Path=bools}" />
    </StackPanel>
</DataTemplate>

Now when I edit the bools (Click them in my ListView ), the source doesn’t get updated, and that’s good, but now I can find no way to save (Commit) the data.
I can’t access neither SPpan nor BGStackPanel from code-behind.
However I have tried the following:

var tmp = (lvBools.View as GridView).Columns[0];
(tmp.CellTemplate.LoadContent() as StackPanel).BindingGroup.BeginEdit();

but also this without success…

EDIT
Ok, so edit II… So I guess that the reason to why the source doesn’t update is because I’m running the Begin/CommitEdit on the Template and not on the actual objects created from the template. So does anyone know how to reach those objects?

Answer 1

Ok, so thanks to Mr E.L Dunn I mannage to solve this one!

So in my first EDIT I suggested that I could maybe add a BindingGroup to the StackPanel in the DataTemplate, and that was kind of in the right direction…

All that’s needed to be done is to add a BindingGroupName to the DataTemplate’s CheckBox.

<StackPanel Name="stpData">
    <StackPanel.BindingGroup>
        <BindingGroup Name="bindingGroup"/>
    </StackPanel.BindingGroup>

    <!-- This works nice! -->
    <TextBox Text="{Binding Path=name}" />
    <CheckBox IsChecked="{Binding Path=enable}" />

    <!-- Now this work nice as well! -->
    <ListView Name="lvBools" ItemsSource="{Binding Path=myList}">
        <ListView.View>
            <GridView>
                <GridViewColumn>
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <StackPanel>
                                <CheckBox IsChecked="{Binding bools, BindingGroupName=bindingGroup}" />
                            </StackPanel>
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>
            </GridView>
        </ListView.View>
    </ListView>
</StackPanel>

Simple as that!