当我尝试更改日历中 DayTitleTemplate 的默认 DataTemplate 时，如果根元素不是Textblock，则应用程序崩溃。
有谁知道如何避免崩溃？
以下是用于演示目的的模板的简化版本。 （Kaxaml ready）
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<Calendar>
<Calendar.CalendarItemStyle>
<Style TargetType="CalendarItem">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="CalendarItem">
<ControlTemplate.Resources>
<!-- ___________________________________________________________________ -->
<!-- This is the default Data template -->
<DataTemplate x:Key="{ComponentResourceKey ResourceId=DayTitleTemplate, TypeInTargetAssembly={x:Type CalendarItem}}">
<TextBlock HorizontalAlignment="Center" Margin="0,6" VerticalAlignment="Center" FontFamily="Verdana" FontSize="9.5" FontWeight="Bold" Foreground="#FF333333" Text="{Binding}"/>
</DataTemplate>
<!-- ___________________________________________________________________ -->
<!-- This is a modified Data template, using this template instead of the Default, makes the XAML crash. -->
<!--<DataTemplate x:Key="{ComponentResourceKey ResourceId=DayTitleTemplate, TypeInTargetAssembly={x:Type CalendarItem}}">
<Grid>
<Rectangle Stroke="Brown" StrokeThickness="0.5"/>
<TextBlock Foreground="#FF333333" FontWeight="Bold" FontSize="9.5" FontFamily="Verdana" HorizontalAlignment="Center" Text="{Binding}" VerticalAlignment="Center"/>
</Grid>
</DataTemplate>-->
<!-- ___________________________________________________________________ -->
</ControlTemplate.Resources>
<Grid x:Name="PART_Root">
<Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1">
<Border BorderBrush="White" BorderThickness="2" CornerRadius="1">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Button x:Name="PART_PreviousButton" Width="28" Height="20" Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Focusable="False">
</Button>
<Button x:Name="PART_HeaderButton" Grid.Column="1" Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center" Focusable="False" FontSize="10.5" FontWeight="Bold">
</Button>
<Button x:Name="PART_NextButton" Width="28" Height="20" Grid.Column="2" Grid.Row="0" HorizontalAlignment="Right" Focusable="False">
</Button>
<Grid x:Name="PART_MonthView" Grid.ColumnSpan="3" Grid.Row="1" HorizontalAlignment="Center" Margin="6,-1,6,6" Visibility="Visible">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
</Grid>
<Grid x:Name="PART_YearView" Grid.ColumnSpan="3" Grid.Row="1" HorizontalAlignment="Center" Margin="6,-3,7,6" Visibility="Hidden">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
</Grid>
</Grid>
</Border>
</Border>
</Grid>
<ControlTemplate.Triggers>
<DataTrigger Binding="{Binding DisplayMode, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type Calendar}}}" Value="Year">
<Setter TargetName="PART_MonthView" Property="Visibility" Value="Hidden"/>
<Setter TargetName="PART_YearView" Property="Visibility" Value="Visible"/>
</DataTrigger>
<DataTrigger Binding="{Binding DisplayMode, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type Calendar}}}" Value="Decade">
<Setter TargetName="PART_MonthView" Property="Visibility" Value="Hidden"/>
<Setter TargetName="PART_YearView" Property="Visibility" Value="Visible"/>
</DataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Calendar.CalendarItemStyle>
</Calendar>
</Grid>
</Page>
这是我得到的StackTrace（抱歉我的系统是日语，这是正常的NullReferenceException）。 我只是将xaml粘贴到一个全新的WPF应用程序项目中。我没有使用任何自动化或其他任何东西。
System.NullReferenceException はハンドルされませんでした。
Message=オブジェクト参照がオブジェクト インスタンスに設定されていません。
Source=PresentationCore
StackTrace:
場所 System.Windows.Automation.Peers.AutomationPeer.EnsureChildren()
場所 System.Windows.Automation.Peers.AutomationPeer.UpdateChildrenInternal(Int32 invalidateLimit)
場所 System.Windows.Automation.Peers.AutomationPeer.UpdateChildren()
場所 System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
場所 System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree()
場所 System.Windows.ContextLayoutManager.fireAutomationEvents()
場所 System.Windows.ContextLayoutManager.UpdateLayout()
場所 System.Windows.UIElement.UpdateLayout()
場所 System.Windows.Interop.HwndSource.Process_WM_SIZE(UIElement rootUIElement, IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam)
場所 System.Windows.Interop.HwndSource.LayoutFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
場所 MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
場所 MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
場所 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
場所 MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
場所 System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
場所 MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
場所 MS.Win32.UnsafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)
場所 System.Windows.Window.ShowHelper(Object booleanBox)
場所 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
場所 MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
場所 System.Windows.Threading.DispatcherOperation.InvokeImpl()
場所 System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
場所 System.Threading.ExecutionContext.runTryCode(Object userData)
場所 System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
場所 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
場所 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
場所 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
場所 System.Windows.Threading.DispatcherOperation.Invoke()
場所 System.Windows.Threading.Dispatcher.ProcessQueue()
場所 System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
場所 MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
場所 MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
場所 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
場所 MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
場所 System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
場所 MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
場所 MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
場所 System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
場所 System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
場所 System.Windows.Threading.Dispatcher.Run()
場所 System.Windows.Application.RunDispatcher(Object ignore)
場所 System.Windows.Application.RunInternal(Window window)
場所 System.Windows.Application.Run(Window window)
場所 System.Windows.Application.Run()
InnerException:
答案 0 :(得分：2)
我遇到了类似的问题，以下帖子帮助了我：http://social.msdn.microsoft.com/Forums/ar/wpf/thread/0ee9954d-0df5-4d61-8dc9-eb50c7a5be99。
在你的情况下，你会改变：
x:Key="{ComponentResourceKey ResourceId=DayTitleTemplate, TypeInTargetAssembly={x:Type CalendarItem}}"
到
x:Key="{x:Static CalendarItem.DayTitleTemplateResourceKey}"