Finding the list of checked item in list of lists - wpf

Question

Let's say I have a questionnaire app, which consists of an ItemsControl with a list of controls each consisting of a Label and a ListBox. The items in each ListBox are checkboxes or radiobuttons or whatever.
My question is: When a checkbox is checked, how do I figure out which Question the checkbox applies to? Should I put a reference to the Question in the Tag property? If so, how would I do that?
The Tag binding code below doesn't work. It binds to the ListBoxItem. How do I bind it to the ItemsControl item?
MainWindow.xaml:
<Window x:Class="ListWithinListTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="450" Width="800">
<Window.Resources>
<ResourceDictionary>
<Style x:Key="ConditionCheckBoxListStyle" TargetType="{x:Type ListBox}">
<Setter Property="SelectionMode" Value="Multiple" />
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="{x:Type ListBoxItem}" >
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBoxItem}">
<CheckBox IsChecked="{Binding IsSelected,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}"
Click="CheckBoxClicked"
Tag="{Binding RelativeSource={RelativeSource TemplatedParent}}"
>
<ContentPresenter></ContentPresenter>
</CheckBox>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
</Window.Resources>
<Grid>
<ItemsControl Name="QuizControl" ItemsSource="{Binding QuizQuestions}" ScrollViewer.CanContentScroll="False">
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Margin="10 0 10 10" VerticalAlignment="Top">
<Label Content="{Binding Text}" />
<ListBox ItemsSource="{Binding Options}"
DisplayMemberPath="Text"
Tag="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}}"
Style="{StaticResource ConditionCheckBoxListStyle}"
/>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</Window>
MainWindow.xaml.cs:
using System.Windows;
using System.Windows.Controls;
namespace ListWithinListTest
{
public class Option
{
public string Text { get; set; }
public bool IsSelected { get; set; } = false;
}
public class Question
{
public string Text { get; set; }
public Option[] Options { get; set; }
}
public class ViewModel
{
public Question[] QuizQuestions { get; set; }
public ViewModel()
{
QuizQuestions = new Question[] {
new Question { Text = "How are you?", Options = new Option[] { new Option { Text = "Good" }, new Option { Text = "Fine" } } },
new Question { Text = "How's your dog?", Options = new Option[] { new Option { Text = "Sleepy" }, new Option { Text = "Hungry" } } },
};
}
}
public partial class MainWindow : Window
{
private ViewModel viewModel;
public MainWindow()
{
InitializeComponent();
this.DataContext = viewModel = new ViewModel();
}
private void CheckBoxClicked(object sender, RoutedEventArgs e)
{
Question question = viewModel.QuizQuestions[???];
}
}
}

Answer 1

Ok, I messed with the Live Visual Tree window until, by process of elimination, I realized that the ListBox is what the Question is going to be bound to. I know now that's a big duh, but that's where I am with this. Then I used RelativeSource AncestorType to find it and the DataSource property to get the question:
MainWindow.xaml:
<CheckBox IsChecked="{Binding IsSelected,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}"
Click="CheckBoxClicked"
Tag="{Binding RelativeSource={RelativeSource AncestorType=ListBox}}"
>
MainWindow.xaml.cs:
private void CheckBoxClicked(object sender, RoutedEventArgs e)
{
CheckBox checkBox = (CheckBox)sender;
ListBox listBox = (ListBox)checkBox.Tag;
Question question = (Question)listBox.DataContext;
Debug.WriteLine(question.Text);
}

Answer 2

You have binded QuizQuestions to the QuizControl, you can get it back from the ItemsSource property.
var questions = (Question[]) QuizControl.ItemsSource;
EDIT
It looks like you got the answer yourself, just another way I would like to suggest to your original question:
Create one more property to your Option class
public class Option
{
public string Text { get; set; }
public bool IsSelected { get; set; } = false;
public int Index{ get; set; }
}
And then add Index to each of your question options.
QuizQuestions = new Question[] {
new Question { Text = "How are you?", Options = new Option[] { new Option { Text = "Good", Index = 0 }, new Option { Text = "Fine", Index = 0 } } },
new Question { Text = "How's your dog?", Options = new Option[] { new Option { Text = "Sleepy", Index = 1 }, new Option { Text = "Hungry", Index = 1 } } },
};
In your CheckBox event you can get the Option Index
private void CheckBoxClicked(object sender, RoutedEventArgs e)
{
var s = (CheckBox)sender;
var op = (Option)s.Tag;
Question question = viewModel.QuizQuestions[op.Index];
}