ComboBox as DataGridTemplateColumn SelectedValue not updating bound property
I am having trouble implementing this CustComboBox (renamed MultiColumnComboBox) with a DataGrid popup into a DataGridTemplateColumn: https://www.codeproject.com/Articles/43074/WPF-Custom-ComboBox
Here's a link to SampleApp I threw together to show my current implementation and issues: https://drive.google.com/file/d/1ChZKjeppf-J04j3RGr6k8tPUE2W8oBBc/view?usp=sharing
In the example I have two Objects:
SampleApp MainWindow.vb:
Private _ToolObjCollection As New ObservableCollection(Of ToolObj)
Public Property ToolObjCollection As ObservableCollection(Of ToolObj)
Get
Return _ToolObjCollection
End Get
Set(value As ObservableCollection(Of ToolObj))
_ToolObjCollection = value
End Set
End Property
Private _ConnectionPairCollection As New ObservableCollection(Of ConnectionPair)
Public Property ConnectionPairCollection As ObservableCollection(Of ConnectionPair)
Get
Return _ConnectionPairCollection
End Get
Set(value As ObservableCollection(Of ConnectionPair))
_ConnectionPairCollection = value
End Set
End Property
Private _TestTool As New ToolObj("conn2")
Public Property TestTool As ToolObj
Get
Return _TestTool
End Get
Set(value As ToolObj)
_TestTool = value
End Set
End Property
Sub New()
InitializeComponent()
_ToolObjCollection.Add(New ToolObj("conn1"))
_ToolObjCollection.Add(New ToolObj("conn2"))
_ConnectionPairCollection.Add(New ConnectionPair("conn1", "eqconn1"))
_ConnectionPairCollection.Add(New ConnectionPair("conn2", "eqconn2"))
DataContext = Me
End Sub
I want to bind ItemsSource of the Combo Popup to ConnectionPairCollection, and I want the selection to update the ConnectionT property on my ToolObj.
When doing this with the MultiColumnComboBox outside of a DataGridTemplateColumn, everything seems to work fine. Implementation looks like this:
<local:MultiColumnComboBox
DisplayMemberPath="Connection"
ItemsSource="{Binding ConnectionPairCollection}"
SelectedValue="{Binding TestTool.ConnectionT}"
SelectedValuePath="Connection">
<DataGridTextColumn
Header="Connection"
Binding="{Binding Connection}" />
<DataGridTextColumn
Header="EQ Connection"
Binding="{Binding EQConnection}" />
</local:MultiColumnComboBox>
When I put the MultiColumnComboBox in a DataGridTemplateColumn of a DataGrid with its ItemsSource bound to ToolObjCollection, the binding only works one way. It correctly receives SelectedValue from my ToolObj and registers the proper selection in the popup, but changing the selection of the ComboBox does not update the value of the ToolObj. Implementation looks like this:
<DataGrid
Margin="0"
Grid.Row="1"
ItemsSource="{Binding ToolObjCollection}"
Tag="{Binding ConnectionPairCollection}">
<DataGrid.Columns>
<DataGridTemplateColumn
Header="TemplatedMultiColumnCombo">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<local:MultiColumnComboBox
DisplayMemberPath="Connection"
ItemsSource="{Binding DataContext.ConnectionPairCollection, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}}"
SelectedValue="{Binding ConnectionT}"
SelectedValuePath="Connection">
<DataGridTextColumn
Header="Connection"
Binding="{Binding Connection}" />
<DataGridTextColumn
Header="EQ Connection"
Binding="{Binding EQConnection}" />
</local:MultiColumnComboBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
I've tried explicitly setting Binding Mode of SelectedValue to TwoWay but it does nothing (as expected, since TwoWay doesn't need to explicitly be set in the first implementation of the MultiColumnCombo)
Is there something I'm missing? Or perhaps some added coding structure I need to add to either Object class or MainWindow codebehind?
For Reference, my ported version of the CustComboBox:
MultiColumnComboBox.vb
' Follow steps 1a or 1b and then 2 to use this custom control in a XAML file.
'
' Step 1a) Using this custom control in a XAML file that exists in the current project.
' Add this XmlNamespace attribute to the root element of the markup file where it is
' to be used:
'
' xmlns:MyNamespace="clr-namespace:WinSurvWPF"
'
'
' Step 1b) Using this custom control in a XAML file that exists in a different project.
' Add this XmlNamespace attribute to the root element of the markup file where it is
' to be used:
'
' xmlns:MyNamespace="clr-namespace:WinSurvWPF;assembly=WinSurvWPF"
'
' You will also need to add a project reference from the project where the XAML file lives
' to this project and Rebuild to avoid compilation errors:
'
' Right click on the target project in the Solution Explorer and
' "Add Reference"->"Projects"->[Browse to and select this project]
'
'
' Step 2)
' Go ahead and use your control in the XAML file. Note that Intellisense in the
' XML editor does not currently work on custom controls and its child elements.
'
' <MyNamespace:MultiColumnComboBox/>
'
Imports System.ComponentModel
Imports System.Windows.Markup
Imports System.Collections.ObjectModel
Imports System.Windows.Controls.Primitives
Imports System.Runtime.CompilerServices
''' <summary>
'''
''' </summary>
<DefaultProperty("Columns")>
<ContentProperty("Columns")>
Public Class MultiColumnComboBox
Inherits ComboBox
Implements INotifyPropertyChanged
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Private Sub NotifyPropertyChanged(<CallerMemberName()> Optional ByVal propertyName As String = Nothing)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
End Sub
Const partPopupDataGrid As String = "PART_PopupDataGrid"
'Columns of DataGrid
Private _Columns As ObservableCollection(Of DataGridTextColumn)
'Attached DataGrid control
Private PopupDataGrid As DataGrid
Shared Sub New()
DefaultStyleKeyProperty.OverrideMetadata(GetType(MultiColumnComboBox), New FrameworkPropertyMetadata(GetType(MultiColumnComboBox)))
End Sub
'The property is default and Content property for CustComboBox
<DesignerSerializationVisibility(DesignerSerializationVisibility.Content)>
Public ReadOnly Property Columns() As ObservableCollection(Of DataGridTextColumn)
Get
If Me._Columns Is Nothing Then
Me._Columns = New ObservableCollection(Of DataGridTextColumn)()
End If
Return Me._Columns
End Get
End Property
'Apply theme and attach columns to DataGrid popupo control
Public Overrides Sub OnApplyTemplate()
If PopupDataGrid Is Nothing Then
PopupDataGrid = TryCast(Me.Template.FindName(partPopupDataGrid, Me), DataGrid)
If PopupDataGrid IsNot Nothing AndAlso _Columns IsNot Nothing Then
'Add columns to DataGrid columns
For i As Integer = 0 To _Columns.Count - 1
PopupDataGrid.Columns.Add(_Columns(i))
Next
'Add event handler for DataGrid popup
PopupDataGrid.AddHandler(PreviewMouseDownEvent, New MouseButtonEventHandler(AddressOf PopupDataGrid_MouseDown))
PopupDataGrid.AddHandler(SelectionChangedEvent, New SelectionChangedEventHandler(AddressOf PopupDataGrid_SelectionChanged))
End If
End If
'Call base class method
MyBase.OnApplyTemplate()
End Sub
'Synchronize selection between Combo and DataGrid popup
Private Sub PopupDataGrid_SelectionChanged(sender As Object, e As SelectionChangedEventArgs)
'When open in Blend prevent raising exception
If Not DesignerProperties.GetIsInDesignMode(Me) Then
Dim dg As DataGrid = TryCast(sender, DataGrid)
If dg IsNot Nothing Then
Me.SelectedItem = dg.SelectedItem
Me.SelectedValue = dg.SelectedValue
Me.SelectedIndex = dg.SelectedIndex
Me.SelectedValuePath = dg.SelectedValuePath
End If
End If
End Sub
'Event for DataGrid popup MouseDown
Private Sub PopupDataGrid_MouseDown(sender As Object, e As MouseButtonEventArgs)
Dim dg As DataGrid = TryCast(sender, DataGrid)
If dg IsNot Nothing Then
Dim dep As DependencyObject = DirectCast(e.OriginalSource, DependencyObject)
' iteratively traverse the visual tree and stop when dep is one of ..
While (dep IsNot Nothing) AndAlso Not (TypeOf dep Is DataGridCell) AndAlso Not (TypeOf dep Is DataGridColumnHeader)
dep = VisualTreeHelper.GetParent(dep)
End While
If dep Is Nothing Then
Return
End If
' do something
If TypeOf dep Is DataGridColumnHeader Then
End If
'When user clicks to DataGrid cell, popup have to be closed
If TypeOf dep Is DataGridCell Then
Me.IsDropDownOpen = False
End If
End If
End Sub
'When selection changed in combobox (pressing arrow key down or up) must be synchronized with opened DataGrid popup
Protected Overrides Sub OnSelectionChanged(e As SelectionChangedEventArgs)
MyBase.OnSelectionChanged(e)
If PopupDataGrid Is Nothing Then
Return
End If
If Not DesignerProperties.GetIsInDesignMode(Me) Then
If IsDropDownOpen Then
PopupDataGrid.SelectedItem = Me.SelectedItem
If PopupDataGrid.SelectedItem IsNot Nothing Then
PopupDataGrid.ScrollIntoView(PopupDataGrid.SelectedItem)
End If
End If
End If
End Sub
Protected Overrides Sub OnDropDownOpened(e As EventArgs)
PopupDataGrid.SelectedItem = Me.SelectedItem
MyBase.OnDropDownOpened(e)
If PopupDataGrid.SelectedItem IsNot Nothing Then
PopupDataGrid.ScrollIntoView(PopupDataGrid.SelectedItem)
End If
End Sub
End Class
MultiColumnComboBox Resource Dictionary:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero"
xmlns:local="clr-namespace:SampleApp">
<Style
x:Key="ComboBoxFocusVisual">
<Setter
Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<Rectangle
Stroke="Black"
StrokeDashArray="1 2"
StrokeThickness="1"
Margin="4,4,21,4"
SnapsToDevicePixels="true" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<LinearGradientBrush
x:Key="ButtonNormalBackground"
EndPoint="0,1"
StartPoint="0,0">
<GradientStop
Color="#F3F3F3"
Offset="0" />
<GradientStop
Color="#EBEBEB"
Offset="0.5" />
<GradientStop
Color="#DDDDDD"
Offset="0.5" />
<GradientStop
Color="#CDCDCD"
Offset="1" />
</LinearGradientBrush>
<SolidColorBrush
x:Key="ButtonNormalBorder"
Color="#FF707070" />
<Geometry
x:Key="DownArrowGeometry">M 0 0 L 3.5 4 L 7 0 Z</Geometry>
<Style
x:Key="ComboBoxReadonlyToggleButton"
TargetType="{x:Type ToggleButton}">
<Setter
Property="OverridesDefaultStyle"
Value="true" />
<Setter
Property="IsTabStop"
Value="false" />
<Setter
Property="Focusable"
Value="false" />
<Setter
Property="ClickMode"
Value="Press" />
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type ToggleButton}">
<Microsoft_Windows_Themes:ButtonChrome
x:Name="Chrome"
SnapsToDevicePixels="true"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
RenderMouseOver="{TemplateBinding IsMouseOver}"
RenderPressed="{TemplateBinding IsPressed}">
<Grid
HorizontalAlignment="Right"
Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
<Path
x:Name="Arrow"
Fill="Black"
HorizontalAlignment="Center"
Margin="3,1,0,0"
VerticalAlignment="Center"
Data="{StaticResource DownArrowGeometry}" />
</Grid>
</Microsoft_Windows_Themes:ButtonChrome>
<ControlTemplate.Triggers>
<Trigger
Property="IsChecked"
Value="true">
<Setter
Property="RenderPressed"
TargetName="Chrome"
Value="true" />
</Trigger>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Fill"
TargetName="Arrow"
Value="#AFAFAF" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<LinearGradientBrush
x:Key="TextBoxBorder"
EndPoint="0,20"
StartPoint="0,0"
MappingMode="Absolute">
<GradientStop
Color="#ABADB3"
Offset="0.05" />
<GradientStop
Color="#E2E3EA"
Offset="0.07" />
<GradientStop
Color="#E3E9EF"
Offset="1" />
</LinearGradientBrush>
<Style
x:Key="ComboBoxEditableTextBox"
TargetType="{x:Type TextBox}">
<Setter
Property="OverridesDefaultStyle"
Value="true" />
<Setter
Property="AllowDrop"
Value="true" />
<Setter
Property="MinWidth"
Value="0" />
<Setter
Property="MinHeight"
Value="0" />
<Setter
Property="FocusVisualStyle"
Value="{x:Null}" />
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type TextBox}">
<ScrollViewer
x:Name="PART_ContentHost"
Background="Transparent"
Focusable="false"
HorizontalScrollBarVisibility="Hidden"
VerticalScrollBarVisibility="Hidden" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style
x:Key="ComboBoxToggleButton"
TargetType="{x:Type ToggleButton}">
<Setter
Property="OverridesDefaultStyle"
Value="true" />
<Setter
Property="IsTabStop"
Value="false" />
<Setter
Property="Focusable"
Value="false" />
<Setter
Property="ClickMode"
Value="Press" />
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type ToggleButton}">
<Microsoft_Windows_Themes:ButtonChrome
x:Name="Chrome"
Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}"
SnapsToDevicePixels="true"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
RenderMouseOver="{TemplateBinding IsMouseOver}"
RenderPressed="{TemplateBinding IsPressed}"
RoundCorners="false">
<Path
x:Name="Arrow"
Fill="Black"
HorizontalAlignment="Center"
Margin="0,1,0,0"
VerticalAlignment="Center"
Data="{StaticResource DownArrowGeometry}" />
</Microsoft_Windows_Themes:ButtonChrome>
<ControlTemplate.Triggers>
<Trigger
Property="IsChecked"
Value="true">
<Setter
Property="RenderPressed"
TargetName="Chrome"
Value="true" />
</Trigger>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Fill"
TargetName="Arrow"
Value="#AFAFAF" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<ControlTemplate
x:Key="ComboBoxEditableTemplate"
TargetType="{x:Type local:MultiColumnComboBox}">
<Grid
x:Name="Placement"
SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition
Width="*" />
<ColumnDefinition
Width="Auto" />
</Grid.ColumnDefinitions>
<Popup
x:Name="PART_Popup"
AllowsTransparency="true"
IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}"
Placement="Bottom"
PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}"
Grid.ColumnSpan="2">
<Microsoft_Windows_Themes:SystemDropShadowChrome
x:Name="Shdw"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
MinWidth="{Binding ActualWidth, ElementName=Placement}"
Color="Transparent">
<Border
x:Name="DropDownBorder"
Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}"
BorderThickness="1">
<DataGrid
x:Name="PART_PopupDataGrid"
ItemsSource="{TemplateBinding ItemsSource}"
AutoGenerateColumns="False"
IsReadOnly="True"
IsSynchronizedWithCurrentItem="False"
SelectionMode="Single"
HeadersVisibility="Column"
SelectedIndex="{TemplateBinding SelectedIndex}"
DisplayMemberPath="{TemplateBinding DisplayMemberPath}"
Focusable="False"
SelectedItem="{TemplateBinding SelectedItem}"
SelectedValue="{TemplateBinding SelectedValue}"
SelectedValuePath="{TemplateBinding SelectedValuePath}"
RowDetailsVisibilityMode="Collapsed"
Tag="{TemplateBinding Tag}"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
IsTextSearchEnabled="{TemplateBinding IsTextSearchEnabled}"
CanUserSortColumns="True">
</DataGrid>
</Border>
</Microsoft_Windows_Themes:SystemDropShadowChrome>
</Popup>
<Microsoft_Windows_Themes:ListBoxChrome
x:Name="Border"
Grid.ColumnSpan="2"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
RenderFocused="{TemplateBinding IsKeyboardFocusWithin}"
RenderMouseOver="{TemplateBinding IsMouseOver}" />
<TextBox
x:Name="PART_EditableTextBox"
Margin="{TemplateBinding Padding}"
Style="{StaticResource ComboBoxEditableTextBox}"
HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}" />
<ToggleButton
Style="{StaticResource ComboBoxToggleButton}"
Grid.Column="1"
IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" />
</Grid>
<ControlTemplate.Triggers>
<Trigger
Property="IsKeyboardFocusWithin"
Value="true">
<Setter
Property="Foreground"
Value="Black" />
</Trigger>
<Trigger
Property="IsDropDownOpen"
Value="true">
<Setter
Property="RenderFocused"
TargetName="Border"
Value="true" />
</Trigger>
<Trigger
Property="HasItems"
Value="false">
<Setter
Property="Height"
TargetName="DropDownBorder"
Value="95" />
</Trigger>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
<Setter
Property="Background"
Value="#FFF4F4F4" />
</Trigger>
<Trigger
Property="IsGrouping"
Value="true">
<Setter
Property="ScrollViewer.CanContentScroll"
Value="false" />
</Trigger>
<Trigger
Property="HasDropShadow"
SourceName="PART_Popup"
Value="true">
<Setter
Property="Margin"
TargetName="Shdw"
Value="0,0,5,5" />
<Setter
Property="Color"
TargetName="Shdw"
Value="#71000000" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<Style
TargetType="{x:Type local:MultiColumnComboBox}">
<Setter
Property="FocusVisualStyle"
Value="{StaticResource ComboBoxFocusVisual}" />
<Setter
Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.WindowTextBrushKey}}" />
<Setter
Property="Background"
Value="{StaticResource ButtonNormalBackground}" />
<Setter
Property="BorderBrush"
Value="{StaticResource ButtonNormalBorder}" />
<Setter
Property="BorderThickness"
Value="1" />
<Setter
Property="ScrollViewer.HorizontalScrollBarVisibility"
Value="Auto" />
<Setter
Property="ScrollViewer.VerticalScrollBarVisibility"
Value="Auto" />
<Setter
Property="Padding"
Value="4,3" />
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type local:MultiColumnComboBox}">
<Grid
x:Name="MainGrid"
SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition
Width="*" />
<ColumnDefinition
MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}"
Width="0" />
</Grid.ColumnDefinitions>
<Popup
x:Name="PART_Popup"
Margin="1"
AllowsTransparency="true"
IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}"
Placement="Bottom"
PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}"
Grid.ColumnSpan="2">
<Microsoft_Windows_Themes:SystemDropShadowChrome
x:Name="Shdw"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
MinWidth="{Binding ActualWidth, ElementName=MainGrid}"
Color="Transparent">
<Border
x:Name="DropDownBorder"
Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"
BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}"
BorderThickness="1">
<DataGrid
x:Name="PART_PopupDataGrid"
ItemsSource="{TemplateBinding ItemsSource}"
AutoGenerateColumns="False"
IsReadOnly="True"
IsSynchronizedWithCurrentItem="False"
SelectionMode="Single"
HeadersVisibility="Column"
SelectedIndex="{TemplateBinding SelectedIndex}"
DisplayMemberPath="{TemplateBinding DisplayMemberPath}"
Focusable="False"
SelectedItem="{TemplateBinding SelectedItem}"
SelectedValue="{TemplateBinding SelectedValue}"
SelectedValuePath="{TemplateBinding SelectedValuePath}"
RowDetailsVisibilityMode="Collapsed"
Tag="{TemplateBinding Tag}"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
IsTextSearchEnabled="{TemplateBinding IsTextSearchEnabled}"
CanUserSortColumns="False" />
</Border>
</Microsoft_Windows_Themes:SystemDropShadowChrome>
</Popup>
<ToggleButton
Style="{StaticResource ComboBoxReadonlyToggleButton}"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
Grid.ColumnSpan="2"
IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" />
<ContentPresenter
HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
Margin="{TemplateBinding Padding}"
VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
IsHitTestVisible="false"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
Content="{TemplateBinding SelectionBoxItem}"
ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" />
</Grid>
<ControlTemplate.Triggers>
<Trigger
Property="HasDropShadow"
SourceName="PART_Popup"
Value="true">
<Setter
Property="Margin"
TargetName="Shdw"
Value="0,0,5,5" />
<Setter
Property="Color"
TargetName="Shdw"
Value="#71000000" />
</Trigger>
<Trigger
Property="HasItems"
Value="false">
<Setter
Property="Height"
TargetName="DropDownBorder"
Value="95" />
</Trigger>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
<Setter
Property="Background"
Value="#FFF4F4F4" />
</Trigger>
<Trigger
Property="IsGrouping"
Value="true">
<Setter
Property="ScrollViewer.CanContentScroll"
Value="false" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger
Property="IsEditable"
Value="true">
<Setter
Property="BorderBrush"
Value="{StaticResource TextBoxBorder}" />
<Setter
Property="Background"
Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" />
<Setter
Property="IsTabStop"
Value="false" />
<Setter
Property="Padding"
Value="3" />
<Setter
Property="Template"
Value="{StaticResource ComboBoxEditableTemplate}" />
</Trigger>
</Style.Triggers>
</Style>
</ResourceDictionary>
The problem is that the DataContext is not accessible in a DataGridTemplateColumn. This happens for elements that are not part of the visual or logical tree. You can use a BindingProxy to solve it. Here is how you can do this.
Found a way to get it working, though I'm not sure if it's the most efficient. Either way, I added a dependency property to the MultiColumnComboBox control: BindingPath as String:
Public Shared ReadOnly BindingPathProperty As DependencyProperty =
DependencyProperty.Register("BindingPath", GetType(String), GetType(MultiColumnComboBox))
Public Property BindingPath As String
Get
Return GetValue(BindingPathProperty)
End Get
Set(value As String)
SetValue(BindingPathProperty, value)
End Set
End Property
Then, I modified the SelectionChanged event handler to check for a set BindingPath value, and set the target property via CallByName:
Private Sub PopupDataGrid_SelectionChanged(sender As Object, e As SelectionChangedEventArgs)
If Not DesignerProperties.GetIsInDesignMode(Me) Then
Dim dg As DataGrid = TryCast(sender, DataGrid)
If dg IsNot Nothing Then
Me.SelectedItem = dg.SelectedItem
Me.SelectedValue = dg.SelectedValue
Me.SelectedIndex = dg.SelectedIndex
Me.SelectedValuePath = dg.SelectedValuePath
If BindingPath IsNot Nothing Then
CallByName(Me.DataContext, BindingPath, CallType.Set, Me.SelectedValue)
End If
End If
End If
End Sub
Now, when setting BindingPath of the MultiColumnCombo to "ConnectionT", everything updates properly when making selections to the nested MultiColumnCombo..
<DataGrid
Margin="0"
Grid.Row="1"
ItemsSource="{Binding ToolObjCollection}"
Tag="{Binding ConnectionPairCollection}">
<DataGrid.Resources>
<local:BindingProxy
x:Key="proxy"
Data="{Binding}" />
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridTemplateColumn
Header="TemplatedMultiColumnCombo">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<local:MultiColumnComboBox
DisplayMemberPath="Connection"
ItemsSource="{Binding Data.ConnectionPairCollection, Source={StaticResource proxy}}"
BindingPath="ConnectionT"
SelectedValue="{Binding ConnectionT}"
SelectedValuePath="Connection">
<DataGridTextColumn
Header="Connection"
Binding="{Binding Connection}" />
<DataGridTextColumn
Header="EQ Connection"
Binding="{Binding EQConnection}" />
</local:MultiColumnComboBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
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