c#code for select all wpf datagrid中的复选框

<DataGrid x:Name="dataGrid" AutoGenerateColumns="False" >
    <DataGrid.Columns>
        <DataGridCheckBoxColumn Header="Select" Binding="{Binding IsSelected}" />
        <DataGridTextColumn Header="Name" Binding="{Binding Name}" />
        <DataGridTextColumn Header="Age" Binding="{Binding Age}" />
    </DataGrid.Columns>
</DataGrid>

private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
    foreach (var item in dataGrid.ItemsSource)
    {
        item.IsSelected = true;
    }
}

private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
{
    foreach (var item in dataGrid.ItemsSource)
    {
        item.IsSelected = false;
    }
}

public class DataItem
{
    public string Name { get; set; }
    public int Age { get; set; }
    public bool IsSelected { get; set; }
}