PowerShell WPF DataGrid:提交空行引发异常
我在尝试提交空 DataGrid 行时遇到异常。
System.NullReferenceException: Object reference not set to an instance of an object.
at MS.Internal.Data.PropertyPathWorker.DetermineWhetherDBNullIsValid()
at MS.Internal.Data.PropertyPathWorker.get_IsDBNullValidForUpdate()
at MS.Internal.Data.ClrBindingWorker.get_IsDBNullValidForUpdate()
at System.Windows.Data.BindingExpression.ConvertProposedValue(Object value)
at System.Windows.Data.BindingExpressionBase.UpdateValue()
at System.Windows.Data.BindingExpression.Update(Boolean synchronous)
at System.Windows.Data.BindingExpression.UpdateSource()
at Microsoft.Windows.Controls.DataGridHelper.UpdateSource(FrameworkElement element, DependencyProperty dp)
at Microsoft.Windows.Controls.DataGridTextColumn.CommitCellEdit(FrameworkElement editingElement)
at Microsoft.Windows.Controls.DataGridColumn.CommitEdit(FrameworkElement editingElement)
at Microsoft.Windows.Controls.DataGridCell.CommitEdit()
at Microsoft.Windows.Controls.DataGrid.OnExecutedCommitEdit(ExecutedRoutedEventArgs e)
at Microsoft.Windows.Controls.DataGrid.OnExecutedCommitEdit(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandBinding.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandManager.ExecuteCommandBinding(Object sender, ExecutedRoutedEventArgs e, CommandBinding commandBinding)
at System.Windows.Input.CommandManager.FindCommandBinding(CommandBindingCollection commandBindings, Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.FindCommandBinding(Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.UIElement.OnExecutedThunk(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.ExecutedRoutedEventArgs.InvokeEventHandler(Delegate genericHandler, Object target)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
at System.Windows.Input.RoutedCommand.Execute(Object parameter, IInputElement target)
at Microsoft.Windows.Controls.DataGrid.EndEdit(RoutedCommand command, DataGridCell cellContainer, DataGridEditingUnit editingUnit, Boolean exitEditMode)
at Microsoft.Windows.Controls.DataGrid.CommitEdit(DataGridEditingUnit editingUnit, Boolean exitEditingMode)
at Microsoft.Windows.Controls.DataGrid.CommitAnyEdit()
at Microsoft.Windows.Controls.DataGrid.OnEnterKeyDown(KeyEventArgs e)
at Microsoft.Windows.Controls.DataGrid.OnKeyDown(KeyEventArgs e)
at System.Windows.UIElement.OnKeyDownThunk(Object sender, KeyEventArgs e)
at System.Windows.Input.KeyEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawKeyboardActions actions, Int32 scanCode, Boolean isExtendedKey, Boolean isSystemKey, Int32 virtualKey)
at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(MSG& msg, Boolean& handled)
at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
Exception calling "Run" with "1" argument(s): "Object reference not set to an instance of an object."
重现步骤:
- 转到“新行”
- 按 F2
- 按 ENTER
这可以正常工作:
- 转到“新行”
- 按 F2
- 按 ESC
以及:
- 转到“新行”
- 按 F2
- 输入“sdfdsf”
- 按 ENTER
可以找到源 此处。
我发现了两篇似乎与此问题相关的帖子:
此外,我在 C# 中尝试了类似的代码,并且运行良好。
我该如何解决这个问题?
I get exception trying to commit empty DataGrid row.
System.NullReferenceException: Object reference not set to an instance of an object.
at MS.Internal.Data.PropertyPathWorker.DetermineWhetherDBNullIsValid()
at MS.Internal.Data.PropertyPathWorker.get_IsDBNullValidForUpdate()
at MS.Internal.Data.ClrBindingWorker.get_IsDBNullValidForUpdate()
at System.Windows.Data.BindingExpression.ConvertProposedValue(Object value)
at System.Windows.Data.BindingExpressionBase.UpdateValue()
at System.Windows.Data.BindingExpression.Update(Boolean synchronous)
at System.Windows.Data.BindingExpression.UpdateSource()
at Microsoft.Windows.Controls.DataGridHelper.UpdateSource(FrameworkElement element, DependencyProperty dp)
at Microsoft.Windows.Controls.DataGridTextColumn.CommitCellEdit(FrameworkElement editingElement)
at Microsoft.Windows.Controls.DataGridColumn.CommitEdit(FrameworkElement editingElement)
at Microsoft.Windows.Controls.DataGridCell.CommitEdit()
at Microsoft.Windows.Controls.DataGrid.OnExecutedCommitEdit(ExecutedRoutedEventArgs e)
at Microsoft.Windows.Controls.DataGrid.OnExecutedCommitEdit(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandBinding.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.CommandManager.ExecuteCommandBinding(Object sender, ExecutedRoutedEventArgs e, CommandBinding commandBinding)
at System.Windows.Input.CommandManager.FindCommandBinding(CommandBindingCollection commandBindings, Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.FindCommandBinding(Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
at System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.UIElement.OnExecutedThunk(Object sender, ExecutedRoutedEventArgs e)
at System.Windows.Input.ExecutedRoutedEventArgs.InvokeEventHandler(Delegate genericHandler, Object target)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
at System.Windows.Input.RoutedCommand.Execute(Object parameter, IInputElement target)
at Microsoft.Windows.Controls.DataGrid.EndEdit(RoutedCommand command, DataGridCell cellContainer, DataGridEditingUnit editingUnit, Boolean exitEditMode)
at Microsoft.Windows.Controls.DataGrid.CommitEdit(DataGridEditingUnit editingUnit, Boolean exitEditingMode)
at Microsoft.Windows.Controls.DataGrid.CommitAnyEdit()
at Microsoft.Windows.Controls.DataGrid.OnEnterKeyDown(KeyEventArgs e)
at Microsoft.Windows.Controls.DataGrid.OnKeyDown(KeyEventArgs e)
at System.Windows.UIElement.OnKeyDownThunk(Object sender, KeyEventArgs e)
at System.Windows.Input.KeyEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawKeyboardActions actions, Int32 scanCode, Boolean isExtendedKey, Boolean isSystemKey, Int32 virtualKey)
at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(MSG& msg, Boolean& handled)
at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
Exception calling "Run" with "1" argument(s): "Object reference not set to an instance of an object."
Steps to reproduce:
- Goto "new row"
- Press F2
- Press ENTER
This works ok:
- Goto "new row"
- Press F2
- Press ESC
As well as:
- Goto "new row"
- Press F2
- Type "sdfdsf"
- Press ENTER
Sources can be found here.
I have found two posts that seems to be related to this problem:
Also, I tried similar code in C#, and it worked fine.
How can I fix this issue?
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这似乎是 Microsoft WPF DataGrid 中的一个错误。 如果您还没有这样做,您绝对应该通过 Microsoft Connect 报告此问题。
作为解决方法,您可以在绑定上使用值转换器,以阻止绑定目标上的 NULL 值传输到绑定源,否则会导致 NullReferenceException。 下面是此类转换器的一个示例:
为了将转换器应用到您的绑定,您必须像这样修改您的 XAML:
或者,您可以修改 NullToUnsetConverter.Convert 方法以返回空字符串 当输入值是字符串时,就像您的情况一样。
This seems to be a bug in the Microsoft WPF DataGrid. You should definitely report it through Microsoft Connect, if you haven't already done so.
As a workaround, you could use a value converter on your bindings, to stop NULL values on the binding target from being transferred to the binding source, which will cause the NullReferenceException. Here is an example of such a converter:
In order to apply the converter to your bindings, you'll have to modify your XAML like this:
Alternatively, you could modify the NullToUnsetConverter.Convert method to return an empty string when the input value is a string, like in your case.