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POWPF bound ComboBox with CompositeCollection - setting SelectedItem
 

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    <p>I have a bound WPF comboBox that has an ItemsSource set to a CompositeCollection. I'm trying this to try and accomodate adding &lt;Select> and &lt;Add New...> selections to precede an ObservableCollection of 'regular' objects. What I can't figure out is how to, in code-behind, select one of these added choices.</p> <p>This is how I'm building the CompositeCollection:</p> <pre><code>private CompositeCollection CreateItemsSource(ObservableCollection&lt;T&gt; source) { CompositeCollection cmpc = new CompositeCollection(); cmpc.Add(new ComboBoxItem { Content = "&lt;Select&gt;" }); cmpc.Add(new ComboBoxItem { Content = "&lt;Add New...&gt;" }); var cc1 = new CollectionContainer { Collection = source }; cmpc.Add(cc1); return cmpc; } </code></pre> <p>This is what the ComboBox looks like:</p> <pre><code>&lt;DataTemplate x:Key="LookupComboTemplate"&gt; &lt;TextBlock Text="{Binding}"/&gt; &lt;/DataTemplate&gt; &lt;ComboBox ItemsSource="{Binding SubCategories.ItemsSource}" ItemTemplate="{StaticResource LookupComboTemplate}"&gt; &lt;ComboBox.SelectedItem&gt; &lt;Binding Path="SourceData.SubCategoryObj" Mode="TwoWay"&gt;&lt;/Binding&gt; &lt;/ComboBox.SelectedItem&gt; &lt;/ComboBox&gt; </code></pre> <p>I've got a situation where SelectedItem SourceData.SubCategoryObj is null (it's an optional property). In this case, I want to manually select and display the &lt;Select> choice. But no matter what I do (setting SelectedIndex is ignored, setting SelectedValue to the ComboBoxItem in the CompositeCollection is ignored) I get a blank ComboBox when it renders.</p> <p>I'd appreciate any advice on how I can do this.</p> <p>Thanks! Corey.</p>
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