How to use CompositeCollection in WPF and MVVM

Asked Dec 28 '11 at 21:41

Active Dec 28 '11 at 21:41

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I have a WPF app using MVVM. I have a DataGrid on the form and the DataGrid has a column with a ComboBox that contains an ObservableCollection.

I want to add a "Please Select From List" to the top of the ComboBox. I tried using CompositeCollection to do this but could not get the ObservableCollection list to bind to the combobox, but the "Please Select" did bind OK.

How can I add a "Please select" to the top of the ComboBox in this scenario? Does anyone have an example of this?

Here is what I tried: XAML:

<UserControl.Resources>
    <MyVM:MyViewModel x:Key="MyDataList"/>
</UserControl.Resources>

<ComboBox....   
   <ComboBox.ItemsSource>
       <CompositeCollection>
            <ComboBoxItem>Select Address Type</ComboBoxItem>
                  <CollectionContainer Collection="{Binding Source={StaticResource MyDataList}}" />
       </CompositeCollection>
   </ComboBox.ItemsSource>

asked Dec 28 '11 at 21:41

Jerry

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Try using an `IValueConverter` on the *ItemsSource* property. While in `Convert` method, add a *"Select Address Type"* item at the 0th index. – decyclone Dec 28 '11 at 22:27
Sor your ViewModel is a list. Do you have a datatemplate for your list elements ? – GameAlchemist Dec 29 '11 at 02:00

How to use CompositeCollection in WPF and MVVM

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