DataTemplate 中的按钮如何注册并监听后面代码中按钮的加载事件，但无法访问数据上下文？

Question

I don't understand why a button inside of a datatemplate can know the loaded event is in the code behind, but can't simply use the code behind as the data context.

I know of solutions to solve this, but I'm not sure why it isn't easier to bind a command to a button within a datatemplate.

Xaml

<grid:RadDataGrid Margin="0" ItemsSource="{x:Bind _viewModel.Data, Mode=OneWay}" Width="600" HorizontalAlignment="Left">
            <grid:RadDataGrid.Columns>
                <grid:DataGridTemplateColumn Header="Delete" SizeMode="Fixed">
                    <grid:DataGridTemplateColumn.CellContentTemplate>
                        <DataTemplate>
                            <StackPanel x:Name="stackPanel" Style="{StaticResource ResourceKey=RadDataGridButtonPanel}">
                                <Button Command="{Binding _viewModel.DeleteCommand, ElementName=deleteView}" Loaded="DeleteButton_Loaded">
                                </Button>
                            </StackPanel>
                        </DataTemplate>
                    </grid:DataGridTemplateColumn.CellContentTemplate>
                </grid:DataGridTemplateColumn>
            </grid:RadDataGrid.Columns>
 </grid:RadDataGrid>

Code Behind

        private readonly ViewModel _viewModel;

        public DeleteView()
        {
            this.InitializeComponent();
            _viewModel = new ViewModel();
            this.DataContext = _viewModel;

        }

        private void DeleteButton_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
        {

        }

Answer 1

This is based on how events are being handled with the XAML compiler, and DataContext works. When specifying an eventhandler on your button, the XAML Compiler generates something like this:

var button1 = Page.GetElement("buttonInTemplate") //Some magic to get the button
button1.Loaded += Page.DeleteButton_Loaded;

The button itsself isn't actually aware of the event, instead the code generated from XAML hooks the event to the appropriate button.

The DataContext on the other hand gets handled by the system differently. DataContext is something that propagates down. So your buttons DataContext is determined by walking up the visual tree and finding the first element that provides you with the DataContext.