Silverlight databound ComboBox not refreshing when SelectedValue set - data-binding

Question

I'm experiencing a refresh problem with my databound ComboBox.
The selection is not refreshed when I change the SelectedValue from the code-behind.
Here is a sample I made which illustrates the problem. Am I doing something wrong ?
Thanks !
<navigation:Page x:Class="Views.TestCB"
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:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
d:DesignWidth="640" d:DesignHeight="480"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
Title="TestCB Page">
<Grid x:Name="LayoutRoot">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ComboBox ItemsSource="{Binding AllItems, Mode=TwoWay}" Grid.Row="0" SelectedItem="{Binding SelectedItem, Mode=TwoWay}" DisplayMemberPath="Key" SelectedValuePath="Value" SelectedValue="{Binding SelectedValue, Mode=TwoWay}"/>
<Button Content="Change" Click="Button_Click" Grid.Row="1" />
<Button Content="Display" Click="Button_Click_1" Grid.Row="2" />
</Grid>
</navigation:Page>
public partial class TestCB : Page, INotifyPropertyChanged
{
public TestCB()
{
InitializeComponent();
}
private Random r = new Random();
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
private ObservableCollection<MyClass> allItemsField = new ObservableCollection<MyClass>();
public ObservableCollection<MyClass> AllItems
{
get
{
return this.allItemsField;
}
set
{
if (this.allItemsField != value)
{
this.allItemsField = value;
this.OnPropertyChanged("AllItems");
}
}
}
private MyClass selectedItemField = null;
public MyClass SelectedItem
{
get
{
return this.selectedItemField;
}
set
{
if (this.selectedItemField != value)
{
this.selectedItemField = value;
this.OnPropertyChanged("SelectedItem");
}
}
}
private int selectedValueField;
public int SelectedValue
{
get
{
return this.selectedValueField;
}
set
{
if (this.selectedValueField != value)
{
this.selectedValueField = value;
this.OnPropertyChanged("SelectedValue");
}
}
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
this.SetCombo();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
this.SetCombo();
this.SelectRandom();
}
private void SetCombo()
{
this.AllItems.Clear();
int generated = 0;
while (generated < 10)
{
int val = r.Next(100);
string key = string.Format("Key #{0}", val);
if (!this.AllItems.Any(e => e.Key == key))
{
this.AllItems.Add(new MyClass { Key = key, Value = val });
generated++;
}
}
}
private void SelectRandom()
{
var tmp = this.AllItems[r.Next(this.AllItems.Count)];
this.SelectedValue = tmp.Value;
}
private void Button_Click_1(object sender, RoutedEventArgs e)
{
MessageBox.Show(this.SelectedItem.Key);
}
}
public class MyClass : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
private int valueField;
public int Value
{
get
{
return this.valueField;
}
set
{
if (this.valueField != value)
{
this.valueField = value;
this.OnPropertyChanged("Value");
}
}
}
private string keyField = string.Empty;
public string Key
{
get
{
return this.keyField;
}
set
{
if (this.keyField != value)
{
this.keyField = value;
this.OnPropertyChanged("Key");
}
}
}
}
EDIT: Please note that in my program, the ComboBox is part of a ListBoxItem (the ListBox being also databound), so I can't access it directly to reset the binding/force a reload.

Answer 1

I finally used the combobox found here : http://forums.lhotka.net/forums/p/9786/45971.aspx
It corrected my SelectedValue binding problem.

Answer 2

Have you tried setting SelectedItem instead? SelectedValue has some know issues.