Adding the Click = "...." button causes the "Link to the object is not installed in the instance of the object" at startup

Here is the code I use to create the window:

<Grid x:Name="LayoutRoot">
    <TreeView DataContext="{Binding ElementName=UserControl, Mode=OneWay}"
        ....
        ItemsSource="{Binding UrlList}" ItemContainerStyle="{DynamicResource TreeViewItemStyle}" >
        <TreeView.Resources>
            <HierarchicalDataTemplate DataType="{x:Type local:UrlList}">
                <Grid Margin="-15,0,0,0">                       
                    <Expander>
                        <Expander.Header>
                            ....
                        </Expander.Header>
                        <StackPanel>
                            ....
                            <DataGrid ItemsSource="{Binding List}" Margin="0,10,0,0" AutoGenerateColumns="False">
                                <DataGrid.Columns>
                                    ....
                                    <DataGridTemplateColumn>
                                        <DataGridTemplateColumn.CellTemplate>
                                            <DataTemplate>
                                                <Button Content="..."  Click="EditUri_Click"/>
                                            </DataTemplate>                                             
                                        </DataGridTemplateColumn.CellTemplate>                                          
                                    </DataGridTemplateColumn>
                                </DataGrid.Columns>
                            </DataGrid>
                        </StackPanel>       
                    </Expander>
                </Grid>
            </HierarchicalDataTemplate>
        </TreeView.Resources>
    </TreeView>
</Grid>

when I use <Button Content="..." />, the application starts normally, when I use <Button Content="..." Click="EditUri_Click"/>, I get the following exception:

    System.NullReferenceException was unhandled
  Message=Object reference not set to an instance of an object.
  Source=MyApp
  StackTrace:
       at UrlListInfoPanel.System.Windows.Markup.IStyleConnector.Connect(Int32 connectionId, Object target) in ...\UrlListInfoPanel.xaml:line 152[this is where the button is]
       at System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlReader templateReader, XamlObjectWriter currentWriter)
       at System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlObjectWriter objectWriter)
       at System.Windows.FrameworkTemplate.LoadOptimizedTemplateContent(DependencyObject container, IComponentConnector componentConnector, IStyleConnector styleConnector, List`1 affectedChildren, UncommonField`1 templatedNonFeChildrenField)
       at System.Windows.FrameworkTemplate.LoadContent(DependencyObject container, List`1 affectedChildren)
       at System.Windows.StyleHelper.ApplyTemplateContent(UncommonField`1 dataField, DependencyObject container, FrameworkElementFactory templateRoot, Int32 lastChildIndex, HybridDictionary childIndexFromChildID, FrameworkTemplate frameworkTemplate)
       at System.Windows.FrameworkTemplate.ApplyTemplateContent(UncommonField`1 templateDataField, FrameworkElement container)
       at System.Windows.FrameworkElement.ApplyTemplate()
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Border.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureCell(Int32 cell, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureCellsGroup(Int32 cellsHead, Size referenceSize, Boolean ignoreDesiredSizeU, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.TreeViewItem.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.StackPanel.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at MS.Internal.Helper.MeasureElementWithSingleChild(UIElement element, Size constraint)
       at System.Windows.Controls.ItemsPresenter.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at MS.Internal.Helper.MeasureElementWithSingleChild(UIElement element, Size constraint)
       at System.Windows.Controls.ScrollContentPresenter.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureCell(Int32 cell, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureCellsGroup(Int32 cellsHead, Size referenceSize, Boolean ignoreDesiredSizeU, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.ScrollViewer.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Border.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Control.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at MS.Internal.Helper.MeasureElementWithSingleChild(UIElement element, Size constraint)
       at System.Windows.Controls.ContentPresenter.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Border.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Control.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureCell(Int32 cell, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureCellsGroup(Int32 cellsHead, Size referenceSize, Boolean ignoreDesiredSizeU, Boolean forceInfinityV)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at MS.Internal.Helper.MeasureElementWithSingleChild(UIElement element, Size constraint)
       at System.Windows.Controls.ContentPresenter.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Documents.AdornerDecorator.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Border.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Controls.Grid.MeasureOverride(Size constraint)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Window.MeasureOverrideHelper(Size constraint)
       at System.Windows.Window.MeasureOverride(Size availableSize)
       at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
       at System.Windows.UIElement.Measure(Size availableSize)
       at System.Windows.Interop.HwndSource.SetLayoutSize()
       at System.Windows.Interop.HwndSource.set_RootVisualInternal(Visual value)
       at System.Windows.Window.SetRootVisualAndUpdateSTC()
       at System.Windows.Window.SetupInitialState(Double requestedTop, Double requestedLeft, Double requestedWidth, Double requestedHeight)
       at System.Windows.Window.CreateSourceWindow(Boolean duringShow)
       at System.Windows.Window.ShowHelper(Object booleanBox)
       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.Threading.ExecutionContext.runTryCode(Object userData)
       at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
       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.Application.RunInternal(Window window)
       at System.Windows.Application.Run()
       at BookmarkWizV2.App.Main() in App.g.cs:line 0
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       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.Threading.ThreadHelper.ThreadStart()
  InnerException: 

Where does this come from, and how can I fix it?

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3 answers

I ran into this problem before, WPF doesn't seem to like adding events to controls in data templates. I solved this by replacing the event with a team that performed the same thing.

Edit:

Maybe try something like this ...

<DataGrid ItemsSource="{Binding List}" Margin="0,10,0,0" AutoGenerateColumns="False">
    <DataGrid.CommandBindings>
        <CommandBinding Command="commands:Commands.EditURI" CanExecute="CommandBinding_CanExecute" Executed="CommandBinding_Executed"/>
    </DataGrid.CommandBindings>
    <DataGrid.Columns>
        <DataGridTemplateColumn>
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Button Content="..." Command="controls:Commands.EditURI"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

You can customize the class of commands somewhere (refer to it in uri, I used commands :)

public class Commands
{
    public static RoutedCommand EditURI = new RoutedCommand("EditURI", typeof(Commands));
}

...

    private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
    {
        e.CanExecute = true;
    }

    private void CommandBinding_Executed(object sender, ExecutedRoutedEventArgs e)
    {
         //Your code to execute
    }

, , , , . , , , .

+5

When a data template is analyzed using the xaml analyzer, it is a resource, the resource has no code, unless you define a resource dictionary with the code behind, so you cannot refer to the methods in your window when defining resources. you can only use material related to the context of these resources or other resources, as KDiTraglia said

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