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I have a VS2008, C# WPF, Excel AddIn; Under some case, My addin throws exception like
A first chance exception of type 'System.InvalidOperationException' occurred in PresentationFramework.dll
A first chance exception of type 'System.NullReferenceException' occurred in PresentationFramework.dll
but I could not locate where the exception comes from. I know it is b/c data binding. but unable to find out where. Each time I step in, VS tracks to a method which executes w/o error, then after that, the exception throws and but no clue of which line of code.
I have been struggling this for days and could not make a little progress. Pls help out. thanks
Edit, it is too long to fit in comment. So I just put xaml file here. @xmal file that throws the exception. It is DataGridComboBoxColumn that throws the exception
<UserControl x:Class="View.BasketView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dg="http://schemas.microsoft.com/wpf/2008/toolkit" >
<UserControl.Resources>
<sharedC:FunctionToHiddenVisibility x:Key="enumSRToVis"/>
<sharedC:FunctionToHiddenVisibility x:Key="enumCSToVis"/>
<Style x:Key="DataGridRowStyle" TargetType="{x:Type dg:DataGridRow}">
<Style.Triggers>
<Trigger Property="AlternationIndex" Value="1" >
<Setter Property="Background" Value="Beige" />
</Trigger>
</Style.Triggers>
<Setter Property="AllowDrop" Value="True" />
<Setter Property="Margin" Value="0 2 0 2" />
</Style>
<Style x:Key="DataGridStyle" TargetType="{x:Type dg:DataGrid}">
<Setter Property="AlternationCount" Value="2" />
<Setter Property="RowStyle" Value="{StaticResource DataGridRowStyle}" />
</Style>
<Style TargetType="{x:Type MenuItem}">
<Style.Triggers>
<Trigger Property="MenuItem.IsHighlighted" Value="True" >
<Setter Property="BorderBrush" >
<Setter.Value>
<SolidColorBrush Color="Gray"></SolidColorBrush>
</Setter.Value>
</Setter>
<Setter Property="BorderThickness" Value="1"/>
</Trigger>
</Style.Triggers>
</Style>
</UserControl.Resources>
<GroupBox>
<GroupBox.Header>
<TextBlock FontSize="14" FontFamily="Verdana" Text="{Binding Header,Mode=OneWay}"></TextBlock>
</GroupBox.Header>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="33"></RowDefinition>
<RowDefinition Height="*" ></RowDefinition>
<RowDefinition Height="Auto"></RowDefinition>
</Grid.RowDefinitions>
<Border Margin="2 2 2 0">
<Grid>
<Menu Background="Transparent">
<Menu.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Transparent" />
</Menu.Resources>
<MenuItem IsEnabled="{Binding IsItemSelected}" Click="EditClick" ToolTip="Edit Relation(s)" Background="Transparent">
<MenuItem.Header>
<Image Width="16" Height="16" Source="{Binding EditImageFilePath}"/>
</MenuItem.Header>
</MenuItem>
<MenuItem IsEnabled="{Binding IsItemSelected}" Click="DeleteClick" ToolTip="Delete Relation(s)" Background="Transparent">
<MenuItem.Header>
<Image Width="16" Height="16" Source="{Binding DeleteImageFilePath}"/>
</MenuItem.Header>
</MenuItem>
</Menu>
</Grid>
</Border>
<dg:DataGrid Grid.Row="1" x:Name="basketDG" Margin="5 0 5 0" Background="White"
AutoGenerateColumns="False"
Style="{StaticResource DataGridStyle}"
SelectionMode="Extended"
GridLinesVisibility="None"
HeadersVisibility="Column" RowDetailsVisibilityMode="VisibleWhenSelected"
ItemsSource="{Binding BasketItems, Mode=OneWay}" CanUserAddRows="False" CanUserDeleteRows="False"
SelectionUnit="FullRow" SelectedItem="{Binding SelectedRelComplete}"
VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Disabled"
SelectionChanged="BasketDgSelectionChanged"
Drop="DataGridDrop"
DragEnter="DataGridDragEnter"
AllowDrop="True"
>
<!-- Column definition -->
<dg:DataGrid.Columns>
<dg:DataGridTextColumn IsReadOnly="True" Width="100" Header="Symbol" Binding="{Binding Name}" >
<dg:DataGridTextColumn.ElementStyle>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="TextWrapping" Value="Wrap" />
</Style>
</dg:DataGridTextColumn.ElementStyle>
</dg:DataGridTextColumn>
<dg:DataGridTextColumn IsReadOnly="True" Width="*" Header="Symbol Description" Binding="{Binding Desc}" >
<dg:DataGridTextColumn.ElementStyle>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="TextTrimming" Value="WordEllipsis" />
</Style>
</dg:DataGridTextColumn.ElementStyle>
</dg:DataGridTextColumn>
<dg:DataGridComboBoxColumn Width="200" Header="Column"
SelectedValueBinding="{Binding Path=RelParams.ColumnName, UpdateSourceTrigger=PropertyChanged}"
DisplayMemberPath="cName"
SelectedValuePath="cName">
<dg:DataGridComboBoxColumn.ElementStyle>
<Style TargetType="ComboBox">
<Setter Property="ItemsSource" Value="{Binding RelInfo.Columns}" />
</Style>
</dg:DataGridComboBoxColumn.ElementStyle>
<dg:DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox">
<Setter Property="ItemsSource" Value="{Binding RelInfo.Columns}" />
</Style>
</dg:DataGridComboBoxColumn.EditingElementStyle>
</dg:DataGridComboBoxColumn>
</dg:DataGrid.Columns>
</dg:DataGrid>
<Grid Grid.Row="2" Margin="0 5 0 0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" ></ColumnDefinition>
<ColumnDefinition Width="Auto" ></ColumnDefinition>
<ColumnDefinition Width="5" ></ColumnDefinition>
<ColumnDefinition Width="Auto" ></ColumnDefinition>
</Grid.ColumnDefinitions>
<StackPanel HorizontalAlignment="Left" Orientation="Horizontal" Grid.Column="0">
<Button Name="BtnSR" Visibility="{Binding SelectedFunction, Converter={StaticResource enumSRToVis}}" IsEnabled="{Binding ItemsExist}" Margin="2" Click="ShowBasketSettings">Basket Settings</Button>
</StackPanel>
<StackPanel HorizontalAlignment="Left" Orientation="Horizontal" Grid.Column="0">
<Button Name="BtnCS" Visibility="{Binding SelectedFunction, Converter={StaticResource enumCSToVis}}" IsEnabled="{Binding OnlyOneFutureItemExist}" Margin="2" Click="ShowCreateCurve">Curve Settings</Button>
</StackPanel>
<StackPanel Grid.Column="1">
<Button Width="50" Name ="BtnClear" ToolTip="Clear Basket" Margin="2" IsEnabled="{Binding ItemsExist}"
Click="BtnClear_Click">Clear</Button>
</StackPanel>
<StackPanel HorizontalAlignment="Right" Orientation="Horizontal" Grid.Column="3">
<Button Visibility ="{Binding ElementName=BtnSR, Path=Visibility}"
ToolTip="Send Series Data to Table"
Name="SendToTable" Margin="2" Command="{Binding SendToTableCommand}"
CommandParameter="{Binding ElementName=SendToTable}">Send to Table</Button>
</StackPanel>
<StackPanel HorizontalAlignment="Right" Orientation="Horizontal" Grid.Column="3">
<Button Visibility="{Binding ElementName=BtnCS, Path=Visibility}"
Name="CreateCurveSurface" Margin="2"
ToolTip="Send Curve Surface to Table"
IsEnabled="{Binding OnlyOneFutureItemExist}"
Click="CreateCurveSurfaceClick"
>Send to Table</Button>
</StackPanel>
</Grid>
</Grid>
</GroupBox>
</UserControl>
Edit: here is stack trace
Name:NullReferenceException Message:Object reference not set to an instance of an object. Target:Void RestoreAttachedItemValue(System.Windows.DependencyObject, System.Windows.DependencyProperty) Stack: at Microsoft.Windows.Controls.DataGridRow.RestoreAttachedItemValue(DependencyObject objectWithProperty, DependencyProperty property) at Microsoft.Windows.Controls.DataGridRow.SyncProperties(Boolean forcePrepareCells) at Microsoft.Windows.Controls.DataGridRow.PrepareRow(Object item, DataGrid owningDataGrid) at Microsoft.Windows.Controls.DataGrid.PrepareContainerForItemOverride(DependencyObject element, Object item) at System.Windows.Controls.ItemsControl.MS.Internal.Controls.IGeneratorHost.PrepareItemContainer(DependencyObject container, Object item) at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.PrepareItemContainer(DependencyObject container) at System.Windows.Controls.VirtualizingStackPanel.InsertContainer(Int32 childIndex, UIElement container, Boolean isRecycled) at System.Windows.Controls.VirtualizingStackPanel.AddContainerFromGenerator(Int32 childIndex, UIElement child, Boolean newlyRealized) at System.Windows.Controls.VirtualizingStackPanel.BringIndexIntoView(Int32 index) at Microsoft.Windows.Controls.DataGrid.ScrollRowIntoView(Object item)
at Microsoft.Windows.Controls.DataGrid.OnScrollIntoView(Object arg)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
at System.Windows.Window.ShowHelper(Object booleanBox) at System.Windows.Window.Show() at System.Windows.Window.ShowDialog()
860
I am not sure about the cause of your problem but here are some links on How you can debug the WPF bindings -
How can I debug WPF bindings? http://www.zagstudio.com/blog/486 (WayBackLink)
Debugging Data Bindings in a WPF or Silverlight Application http://blogs.msdn.com/b/wpfsldesigner/archive/2010/06/30/debugging-data-bindings-in-a-wpf-or-silverlight-application.aspx (WayBackLink)
WPF Snippet - Detecting Binding Errors
http://www.switchonthecode.com/tutorials/wpf-snippet-detecting-binding-errors
(WayBackLink)
Debug Databinding Issues in WPF
http://www.wpftutorial.net/DebugDataBinding.html
195
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