presence_new/Presence.Desktop/Views/PresenceView.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:vm="using:Presence.Desktop.ViewModels"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="Presence.Desktop.Views.PresenceView"
             x:DataType="vm:PresenceViewModel">

    <DockPanel  Margin="10" Background="Aquamarine">
		<StackPanel Orientation="Horizontal" Spacing="10" DockPanel.Dock="Top">
			<!-- Выбор группы -->
			<ComboBox ItemsSource="{Binding Groups}" SelectedItem="{Binding SelectedGroup}" Width="200" PlaceholderText="Выберите группу">
				<ComboBox.ItemTemplate>
					<DataTemplate>
						<TextBlock Text="{Binding Name}" />
					</DataTemplate>
				</ComboBox.ItemTemplate>
			</ComboBox>

			<!-- Календарь -->
			<Calendar SelectionMode="SingleRange" SelectedDatesChanged="DatesChanged"/>
			
		</StackPanel>

		<StackPanel Orientation="Horizontal" Spacing="10">
		<!-- Таблица с посещаемостью -->
		<DataGrid AutoGenerateColumns="False" ItemsSource="{Binding AttendanceRecords}" CanUserSortColumns="True"
				SelectionChanged="OnDataGridSelectionChanged">
			<DataGrid.Columns>
				<DataGridTextColumn Header="Дата" Binding="{Binding Date}"/>
				<DataGridTextColumn Header="Номер урока" Binding="{Binding ClassNumber}" />
				<DataGridTextColumn Header="ФИО" Binding="{Binding User.Name}" />
				<DataGridCheckBoxColumn Header="Тип посещаемости" Binding="{Binding IsAttendence, Mode=TwoWay}" />
			</DataGrid.Columns>
		</DataGrid>
		<Button Content="Удалить" Margin="0,10,0,0" Command="{Binding DeleteSelectedPresenceCommand}" />
		
		</StackPanel>
	</DockPanel>
</UserControl>