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EmptySelectionBoxTemplate binding EmptyText

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ComboBox

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answered on 11 May 2012, 02:28 AM

Don't know why it works, but the following seems to do what you are looking for.

<Grid x:Name="LayoutRoot"

<Grid.Resources

<DataTemplate x:Key="emptySelectionBoxTemplate"

<TextBlock FontStyle="Italic" Foreground="Gray" Text="{Binding}"

/>

</DataTemplate

</Grid.Resources

<telerik:RadComboBox VerticalAlignment="top" Width="300" EmptyText="Please select an agency" EmptySelectionBoxTemplate="{StaticResource emptySelectionBoxTemplate}" /

</Grid>

I suspect you could then bind the "EmptyText" property, too.

<telerik:RadComboBox VerticalAlignment="top" Width="300" EmptyText="{Binding FieldName}" EmptySelectionBoxTemplate="{StaticResource emptySelectionBoxTemplate}" />

answered on 24 Jun 2012, 12:20 PM

Hi,

I have a RadComboBox that is as follows;

<telerik:RadComboBox ItemsSource="{Binding LevelOfActivityList}" SelectedItem="{Binding SelectedLevelOfActivity,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" MinWidth="200">
<telerik:RadComboBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Margin="3,0,0,0" HorizontalAlignment="Left" Text="{Binding Level,Mode=TwoWay}" FontWeight="Bold" />
<TextBlock Grid.Row="1" Margin="3,0,0,0" HorizontalAlignment="Left" Text="{Binding Detail,Mode=TwoWay}" />
</Grid>
</DataTemplate>
</telerik:RadComboBox.ItemTemplate>
<telerik:RadComboBox.SelectionBoxTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Margin="3,0,0,0" HorizontalAlignment="Left" Text="{Binding Level, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" FontWeight="Bold" />
</Grid>
</DataTemplate>
</telerik:RadComboBox.SelectionBoxTemplate>
</telerik:RadComboBox>

The LevelOfActivity object is a list that has two properties Level and detail. When I run the application I can select the level of activity okay and its just the level that is displayed on the combobox once I select, that is how I want it to work. My problem is when I set the level of activity from the viewmodel (am using MVVM), i.e SelectedLevelOfActivity.Level, the combobox remains blank, nothing is displayed. I am using RadControls for Silverlight Q1 2012. What am I doing wrong? How do I get the combobox to display what I set in the viewmodel? I have tried setting the IsEditable property to true, setting the TextSearch.TextPath and all but still have not got it to work. Please provide any and all the help you can I need to solve this.

Francis.

answered on 28 Jun 2012, 01:45 AM

Hi Konstantina,

That you for your response, it has provided me with much insight. However, the solution you provide in an MVVM scenario will end up breaking the MVVM. My combo box item list is populated in my viewmodel and when getting items from the database to the view, I set the selected item in the viewmodel. In view of this, I have found that implementing the IEquatable on my class solves the problem. below is the code sample for the benefit of any other person who might run into this problem.

THE CLASS
public class TestModel : INotifyPropertyChanged, IEquatable<TestModel>
{

#region Properties

private string _item1;
public string Item1
{
get { return _item1; }
set
{
_item1 = value;
OnPropertyChanged("Item1");
}
}

private string _detail;
public string Detail
{
get { return _detail; }
set
{
_detail = value;
OnPropertyChanged("Detail");
}
}

#endregion

#region NotifyPropertyChanged

public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}

#endregion

#region IEquatable

public override string ToString()
{
return Item1;
}

public bool Equals(TestModel other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Equals(other.Item1, Item1) && Equals(other.Detail, Detail);
}

public override bool Equals(object obj)
{
if (ReferenceEquals(null, obj)) return false;
if (ReferenceEquals(this, obj)) return true;
if (obj.GetType() != typeof(TestModel)) return false;
return Equals((TestModel)obj);
}

public override int GetHashCode()
{
int result = Item1.GetHashCode();
result = (result*397) ^ (Detail != null ? Detail.GetHashCode() : 0);
return result;
}

public static bool operator == (TestModel left, TestModel right)
{
if (ReferenceEquals(left, null)) return false;
return left.Equals(right);
}

public static bool operator !=(TestModel left,TestModel right)
{
return !(left == right);
}

#endregion
}

THE XAML for the ComboBox.

<telerik:RadComboBox ItemsSource="{Binding TestModelList}" SelectedItem="{Binding SelectedTestModel,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" MinWidth="200"
Text="{Binding SelectedTestModel.Item1, Mode=TwoWay}">
<telerik:RadComboBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Orientation="Horizontal" Margin="3,0,0,0" HorizontalAlignment="Left">
<TextBlock HorizontalAlignment="Left" Text="{Binding Item1,Mode=TwoWay}" FontWeight="Bold"/>
</StackPanel>
<StackPanel Grid.Row="1" Orientation="Horizontal" Margin="3,0,0,0" HorizontalAlignment="Left" >
<Border BorderThickness="2" CornerRadius="10" Background="Azure">
<TextBlock Text="{Binding Detail,Mode=TwoWay}" MinWidth="200" />
</Border>
</StackPanel>
</Grid>
</DataTemplate>
</telerik:RadComboBox.ItemTemplate>
<telerik:RadComboBox.SelectionBoxTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Margin="3,0,0,0" HorizontalAlignment="Left">
<TextBlock Text="{Binding Item1, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" FontWeight="Bold" />
</StackPanel>
</Grid>
</DataTemplate>
</telerik:RadComboBox.SelectionBoxTemplate>
</telerik:RadComboBox>

The viewmodel is easy to setup for anyone with some MVVM knowledge. But that about solves the problem in an MVVM scenario.

Thanks,

Francis.