CompositeCollection breaks ComboBox AutoComplete-Feature?

Question

Hello everybody!

I'm using a WPF ComboBox with IsTextSearchEnabled="True" (Autocomplete) and want to bind its ItemsSource-Property to a CompositeCollection. Unfortunately, the Combobox doesn't seem to recognize the items provided by a CollectionContainer within the CompositeCollection. They are shown, but not selected by AutoComplete.

Please try the example, type in "def". If "def" doesn't get selected, you've reproduced the problem I face. Is there any solution, something that I've overseen or a practical way to work around while having some mergedcollection-capability?

<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <XmlDataProvider x:Key="XData1" XPath="/Info">
        <x:XData>
            <Info xmlns="">
                <Item>def</Item>
                <Item>efg</Item>
            </Info>
        </x:XData>
    </XmlDataProvider>

    <CollectionViewSource x:Key='Data1' Source="{Binding Source={StaticResource XData1}, XPath=Item}" />

</Window.Resources>
<Grid>
    <ComboBox IsEditable="True" IsTextSearchEnabled="True" Margin="0,0,0,283">
        <ComboBox.ItemsSource>
            <CompositeCollection>
                <ComboBoxItem>abc</ComboBoxItem>
                <ComboBoxItem>bcd</ComboBoxItem>
                <ComboBoxItem>cde</ComboBoxItem>
                <CollectionContainer Collection="{Binding Source={StaticResource Data1}}" />
            </CompositeCollection>

        </ComboBox.ItemsSource>
    </ComboBox>
</Grid>
</Window>

Thanks!

- dartrax

Answer 1

*push*

Answer 2

Hi dartrax,

It really looks like an issue. First, I thought it maybe caused by the XML data island, then I replace the XML data with a class named Person, which has one property of type string. But the result it's the same, I will look into it further. Anything new, I will let you know immediately.

Thanks.
Sincerely.

---

Jim Zhou -MSFT

Answer 3

Hi Jim,

thanks for looking into that.

I've played a bit around with the AutoCompleteBox that is shipped with the WPF Toolkit February 2010 Release. The result is, the ComboBox works with the CompositeCollection as long as the Items provide a ToString()-Method. In the end was able to solve/work around (?) my problem.

However, the new AutoCompleteBox does NOT work with CompositeCollections (yet). You'll find the Items covered by a CollectionContainer by typing System.Windows.Data.CollectionContainer into it ;)

(Bug reported here: http://wpf.codeplex.com/WorkItem/View.aspx?WorkItemId=11924)

This is an example with makes it easy to compare the behavior of ComboBox and AutoCompleteBox when it comes to CompositeCollections:

XAML:

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:toolkit="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Input.Toolkit"
    Title="MainWindow" Height="350" Width="525">
    <StackPanel >
        <ComboBox x:Name="ComboBox" IsEditable="True"/>
        <toolkit:AutoCompleteBox x:Name="AutoCompleteBox" IsTextCompletionEnabled="True"/>
        <ListBox x:Name="ListBox"/>
    </StackPanel >
</Window>

Code-Behind:

Partial Class MainWindow
    Public Sub New()
        InitializeComponent()
        Dim CompositeCollection As New CompositeCollection From {New Item("1.0.0"), _
                                                                 New Item("2.0.0"), _
                                                                 New Item("3.0.0"), _
                                                                 New CollectionContainer With {.Collection = New CompositeCollection From {New Item("3.1.0"), _
                                                                                                                                           New Item("3.2.0"), _
                                                                                                                                           New Item("3.3.0"), _
                                                                                                                                           New CollectionContainer With {.Collection = New CompositeCollection From {New Item("3.3.1"), _
                                                                                                                                                                                                                     New Item("3.3.2"), _
                                                                                                                                                                                                                     New Item("3.3.3")}}}}}
        ListBox.ItemsSource = CompositeCollection
        ComboBox.ItemsSource = CompositeCollection
        AutoCompleteBox.ItemsSource = CompositeCollection
    End Sub
End Class

Public Class Item
    Dim Name As String

    Public Sub New(ByVal Name As String)
        Me.Name = Name
    End Sub

    Public Overrides Function ToString() As String
        Return Name
    End Function
End Class

- dartrax