InvalidOperationException: 双向绑定需要 Path 或 XPath。
StackTrace:
   在 System.Windows.Data.BindingExpression.CreateBindingExpression(DependencyObject d, DependencyProperty dp, Binding binding, BindingExpressionBase parent)
   在 System.Windows.Data.BindingGroup.PrepareProposedValuesForUpdate(DependencyObject mentor, Boolean isUpdating)
   在 System.Windows.Data.BindingGroup.UpdateAndValidate(ValidationStep validationStep)
   在 System.Windows.Data.BindingGroup.CommitEdit()
   在 System.Windows.Controls.DataGrid.OnExecutedCommitEdit(ExecutedRoutedEventArgs e)
   在 System.Windows.Input.CommandBinding.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
   在 System.Windows.Input.CommandManager.ExecuteCommandBinding(Object sender, ExecutedRoutedEventArgs e, CommandBinding commandBinding)
   在 System.Windows.Input.CommandManager.FindCommandBinding(Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
   在 System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
   在 System.Windows.Controls.DataGrid.EndEdit(RoutedCommand command, DataGridCell cellContainer, DataGridEditingUnit editingUnit, Boolean exitEditMode)
   在 System.Windows.Controls.DataGrid.OnCurrentCellChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   在 System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   在 System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   在 System.Windows.DependencyObject.SetCurrentValueInternal(DependencyProperty dp, Object value)
   在 System.Windows.Controls.DataGrid.set_CurrentCellContainer(DataGridCell value)
   在 System.Windows.Controls.DataGrid.set_FocusedCell(DataGridCell value)
   在 System.Windows.Controls.DataGridCell.OnAnyGotFocus(Object sender, RoutedEventArgs e)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.FrameworkElement.OnGotFocus(RoutedEventArgs e)
   在 System.Windows.UIElement.IsFocused_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   在 System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   在 System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   在 System.Windows.DependencyObject.SetValue(DependencyPropertyKey key, Object value)
   在 System.Windows.Input.FocusManager.OnFocusedElementChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   在 System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   在 System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   在 System.Windows.Input.FocusManager.SetFocusedElement(DependencyObject element, IInputElement value)
   在 System.Windows.Input.KeyboardNavigation.UpdateFocusedElement(DependencyObject focusTarget)
   在 System.Windows.FrameworkElement.OnGotKeyboardFocus(Object sender, KeyboardFocusChangedEventArgs e)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   在 System.Windows.Input.InputManager.ProcessStagingArea()
   在 System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   在 System.Windows.Input.KeyboardDevice.ChangeFocus(DependencyObject focus, Int32 timestamp)
   在 System.Windows.Input.KeyboardDevice.TryChangeFocus(DependencyObject newFocus, IKeyboardInputProvider keyboardInputProvider, Boolean askOld, Boolean askNew, Boolean forceToNullIfFailed)
   在 System.Windows.Input.KeyboardDevice.Focus(DependencyObject focus, Boolean askOld, Boolean askNew, Boolean forceToNullIfFailed)
   在 System.Windows.Input.KeyboardDevice.Focus(IInputElement element)
   在 System.Windows.UIElement.Focus()
   在 System.Windows.Controls.DataGridCell.OnAnyMouseLeftButtonDown(MouseButtonEventArgs e)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   在 System.Windows.UIElement.OnMouseDownThunk(Object sender, MouseButtonEventArgs e)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   在 System.Windows.Input.InputManager.ProcessStagingArea()
   在 System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   在 System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   在 System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   在 System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)