Bound Grid Collection Cleared NullReferenceException in TypeExtensions.DefaultValue

[Leslie]

I have a grid bound to a collection.  If I invoke something that removes all of the items in the collection, I get a null reference exception with the following call stack, which does not contain any of my code.   I get this error 3 times and I had 3 items in my collection.  Any thoughts?

Leslie

<ce:CmpDataGrid Grid.Row="1" x:Name="dgCost" AutoGenerateColumns="False"  ItemsSource="{Binding bocCurrentCosts}"
    HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" SelectionMode="Single"
    ToolStrip="{Binding ElementName=tsCost}" IsFilteringAllowed="False">
    <ce:CmpDataGrid.Columns>
    <ce:CmpGridViewDataColumn DataMemberBinding="{Binding vendordcname, Mode=TwoWay}" Header="{Binding LStrings._VendorDC, Source={StaticResource Strings}}" IsReadOnly="True" />
    <ce:CmpGridViewDataColumn UniqueName="package" Header="{Binding LStrings._Package, Source={StaticResource Strings}}" IsReadOnly="True" >
    <ce:CmpGridViewDataColumn.CellTemplate>
    <DataTemplate>
        <Grid MinWidth="150">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
                <ColumnDefinition Width="Auto" />
            </Grid.ColumnDefinitions>
            <TextBlock Text="{Binding PackageDescription, Mode=OneWay}" TextWrapping="Wrap" HorizontalAlignment="Left" VerticalAlignment="Center" />
            <Button Grid.Column="1" x:Name="btnFindPackage" VerticalAlignment="Stretch" Click="btnGridFindPackage_Click" Visibility="{Binding IsNewDC, Converter={StaticResource myBoolVisibleConverter}}" ToolTipService.ToolTip="{Binding LStrings._ItemPackageToolTip, Source={StaticResource Strings}}">
                <Image Source="/Repeat.Common.Controls;component/Assets/SymbolSearch.png" />
            </Button>
        </Grid>
    </DataTemplate>
    </ce:CmpGridViewDataColumn.CellTemplate>
    </ce:CmpGridViewDataColumn>
    <ce:CmpGridViewDataColumn DataMemberBinding="{Binding effectivedate, Mode=TwoWay}" Header="{Binding SStrings._BeginDate, Source={StaticResource Strings}}" IsVisible="{Binding IsNewDC, Converter={StaticResource myNotConverter}}" IsReadOnly="True" />
    <ce:CmpGridViewDataColumn UniqueName="uomcost" DataMemberBinding="{Binding uomcost, Mode=TwoWay}" Header="{Binding LStrings._Cost, Source={StaticResource Strings}}"  IsReadOnlyBinding="{Binding IsNewDC, Converter={StaticResource myNotConverter}}" DataFormatString="{}{0:c}" MinWidth="75"/>
    </ce:CmpDataGrid.Columns>
</ce:CmpDataGrid>

> Telerik.Windows.Data!Telerik.Windows.Data.TypeExtensions.DefaultValue(System.Type type = null) + 0x1a bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.ExpressionFactory.DefaltValueExpression(System.Type type = null) + 0x20 bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.ExpressionFactory.MakeMemberAccess(System.Linq.Expressions.Expression instance = null, string memberName = "package", System.Type memberType = null) + 0xa3 bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.ExpressionFactory.MakeMemberAccess(System.Linq.Expressions.Expression instance = {System.Linq.Expressions.TypedParameterExpression}, string memberName = "package", System.Type memberType = null, bool liftMemberAccessToNull = true) + 0x30 bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.PropertyAccessExpressionBuilder.CreateMemberAccessExpressionOverride() + 0x6d bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.MemberAccessExpressionBuilderBase.CreateMemberAccessExpression() + 0x59 bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.Expressions.MemberAccessExpressionBuilderBase.CreateLambdaExpression() + 0x2b bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.BindingToExpressionExtensions.CreateMemberAccessLambdaExpression(System.Windows.Data.Binding binding = {System.Windows.Data.Binding}, System.Type objectType = {System.RuntimeType}, System.Type memberType = null) + 0x7a bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.BindingToExpressionExtensions.CreateUntypedMemberAccessFunc(System.Windows.Data.Binding binding = {System.Windows.Data.Binding}, System.Type objectType = {System.RuntimeType}, System.Type memberType = null) + 0x4c bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.BindingToExpressionExtensions.CreateMemberAccessFunc(System.Windows.Data.Binding binding = {System.Windows.Data.Binding}, System.Type objectType = {System.RuntimeType}, System.Type memberType = null) + 0x30 bytes 
  Telerik.Windows.Data!Telerik.Windows.Data.DataFieldDescriptorExtensions.CreateMemberAccessFunc(Telerik.Windows.Data.IDataFieldDescriptor fieldDescriptor = {Repeat.Common.Controls.CmpGridViewDataColumn}) + 0x7e bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridViewBoundColumnBase.InitializeMemberAccessFunc() + 0x2e bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridViewBoundColumnBase.MemberAccessFunc.get() + 0x29 bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridViewBoundColumnBase.GetCellContent(object item = {Repeat.Library.ceEdtCurrentVendorItemCostsBO}) + 0x2c bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridView.GridViewCell.UpdateCellValue() + 0x7f bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridView.GridViewRow.ProcessDataItemPropertyChanged(string propertyName = "") + 0x87 bytes 
  Telerik.Windows.Controls.GridView!Telerik.Windows.Controls.GridView.GridViewRow.Telerik.Windows.Data.IWeakEventListener<System.ComponentModel.PropertyChangedEventArgs>.ReceiveWeakEvent.AnonymousMethod__1b() + 0x6e bytes 
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  mscorlib.dll!System.Delegate.DynamicInvokeImpl(object[] args) + 0x76 bytes 
  mscorlib.dll!System.Delegate.DynamicInvoke(object[] args) + 0xb bytes 
  System.Windows.dll!System.Windows.Threading.DispatcherOperation.Invoke() + 0x2b bytes 
  System.Windows.dll!System.Windows.Threading.Dispatcher.Dispatch(System.Windows.Threading.DispatcherPriority priority) + 0xcc bytes 
  System.Windows.dll!System.Windows.Threading.Dispatcher.OnInvoke(object context) + 0xa bytes 
  System.Windows.dll!System.Windows.Hosting.CallbackCookie.Invoke(object[] args) + 0x16 bytes 
  System.Windows.Browser.dll!System.Windows.Hosting.ScriptingInterface.InvokeDelegate(System.Windows.Hosting.DelegateWrapper delegateWrapper, System.Windows.Hosting.NativeMethods.ScriptParam[] pParams, ref System.Windows.Hosting.NativeMethods.ScriptParam pResult = {System.Windows.Hosting.NativeMethods.ScriptParam}) + 0x28 bytes 
  System.Windows.Browser.dll!System.Windows.Hosting.ManagedHost.InvokeDelegate(System.IntPtr pHandle, int nParamCount, System.Windows.Hosting.NativeMethods.ScriptParam[] pParams, ref System.Windows.Hosting.NativeMethods.ScriptParam pResult) + 0xe3 bytes 
  [Appdomain Transition] 

[Leslie]

Some additional information, if I remove the column with the cell template, I don't get the error!  If I pare it down to the folliwing, I still get the error.  If I remove the unique name, I don't!

<telerik:GridViewDataColumn UniqueName="package" >
	<telerik:GridViewDataColumn.CellTemplate>
	<DataTemplate>
	</DataTemplate>
	</telerik:GridViewDataColumn.CellTemplate>
</telerik:GridViewDataColumn>

[Vlad]

Hi Leslie,

Can you post more info about the grid version? I see that you do not have DataMemberBinding declared for this column - maybe it will be better to use GridVewColumn instead if you want only templates.

Sincerely yours,
Vlad
the Telerik team

[Leslie]

The Telerik.Windows.Controls.GridView.dll version number is 2010.2.924.1040

Don't I have to use a GridViewDataColumn if the items in the template need to be bound?

I was able to get around the problem by removing the UniqueName and adding

DataMemberBinding="{Binding PackageDescription, Mode=TwoWay}" 

But it still seems like UniqueName should work.

Leslie

[Seth]

Has this been resolved?  I am having a similar issue.

Thanks,
Seth

[Vlad]

Hello Seth,

 Indeed we believe that this is fixed long time ago.

All the best,
Vlad
the Telerik team