Assigning AutomationIds Dynamically in Silverlight

I came across an interesting problem recently:  How do you assign AutomationIds automatically for Items in an ItemsControl?

<UserControl 

    x:Class="ThinkFarAhead.AutoAutomationId.MainPage" 

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

    xmlns:local="clr-namespace:ThinkFarAhead.AutoAutomationId" 

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

    mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400">

  <Grid x:Name="LayoutRoot" Background="White">

    <StackPanel>

      <ItemsControl x:Name="ItemsControl">

        <ItemsControl.ItemTemplate>

          <DataTemplate>

            <TextBlock 

                local:AutomationHelper.Parent=

                    "{Binding ElementName=ItemsControl}"

                local:AutomationHelper.CurrentItem=

                    "{Binding Path=DataContext,

                    RelativeSource={RelativeSource TemplatedParent}}"

                local:AutomationHelper.IndexedId="Message{0}"

                    AutomationProperties.AutomationId=

                        "{Binding (local:AutomationHelper.IndexedId),

                        RelativeSource={RelativeSource Self}}"

                Text="{Binding (AutomationProperties.AutomationId), 

                    RelativeSource={RelativeSource Self}}" />

          </DataTemplate>

        </ItemsControl.ItemTemplate>

      </ItemsControl>

    </StackPanel>

  </Grid>

</UserControl>

 

namespace ThinkFarAhead.AutoAutomationId

{

    using System.Windows;

    using System.Windows.Controls;

    public static class AutomationHelper

    {

        #region Constants and Fields

        public static DependencyProperty CurrentItemProperty =

            DependencyProperty.RegisterAttached(

                "CurrentItem",

                typeof(object),

                typeof(AutomationHelper),

                new PropertyMetadata(null)

            );

        public static DependencyProperty IndexedIdProperty =

            DependencyProperty.RegisterAttached(

                "IndexedId",

                typeof(string),

                typeof(AutomationHelper),

                new PropertyMetadata(null)

            );

        public static DependencyProperty ParentProperty =

            DependencyProperty.RegisterAttached(

                "Parent",

                typeof(ItemsControl),

                typeof(AutomationHelper),

                new PropertyMetadata(null)

            );

        #endregion

        #region Public Methods

        public static object GetCurrentItem(DependencyObject element)

        {

            return element.GetValue(CurrentItemProperty);

        }

        public static string GetIndexedId(DependencyObject element)

        {

            return element.GetValue(IndexedIdProperty) as string;

        }

        public static ItemsControl GetParent(DependencyObject element)

        {

            return element.GetValue(ParentProperty) as ItemsControl;

        }

        public static void SetCurrentItem

        (

            DependencyObject element, object value

        )

        {

            element.SetValue(CurrentItemProperty, value);

        }

        public static void SetIndexedId

        (

            DependencyObject element, string value

        )

        {

            value = string.Format(value, 

                GetParent(element)

                .Items

                .IndexOf(GetCurrentItem(element)));

            element.SetValue(IndexedIdProperty, value);

        }

        public static void SetParent

        (

            DependencyObject element, ItemsControl value

        )

        {

            element.SetValue(ParentProperty, value);

        }

        #endregion

    }

}

 

namespace ThinkFarAhead.AutoAutomationId

{

    using System.Collections.Generic;

    using System.Windows.Controls;

    public partial class MainPage : UserControl

    {

        #region Constructors and Destructors

        public MainPage()

        {

            this.InitializeComponent();

            var list = new List<string>();

            list.Add("Zero");

            list.Add("One");

            list.Add("Two");

            list.Add("Three");

            list.Add("Four");

            list.Add("Five");

            list.Add("Six");

            list.Add("Seven");

            list.Add("Eight");

            list.Add("Nine");

            list.Add("Ten");

            this.ItemsControl.ItemsSource = list;

        }

        #endregion

    }

}

 

Hope it helps somebody!

 

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