Displaying RowDetails Programmatically - wpf

Question

I have a DataGrid (the official one) with SelectionUnit="Cell". When the user selects a cell, I'd like to show the row details for the corresponding row. This is apparently not the default behavior, and I can't seem to figure out how to accomplish this.
Here's my XAML:
<UserControl x:Class="View.Test"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<UserControl.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="../AppResources.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</UserControl.Resources>
<Grid>
<DataGrid AutoGenerateColumns="False"
ItemsSource="{Binding Path=Fields}"
BorderBrush="Transparent"
HeadersVisibility="Column"
SelectionMode="Single"
SelectionUnit="Cell"
CanUserAddRows="False"
CanUserDeleteRows="False"
CanUserSortColumns="False"
IsTextSearchEnabled="True"
x:Name="EntryGrid"
>
<DataGrid.Columns>
<DataGridTextColumn Header="Name" Binding="{Binding Path=Name}" Width="Auto" IsReadOnly="True"/>
<DataGridTemplateColumn Header="Value" Width="Auto" x:Name="valueColumn" MinWidth="60" MaxWidth="90">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=DisplayValue}" TextTrimming="CharacterEllipsis" ToolTip="{Binding Path=Text, RelativeSource={RelativeSource Self}}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<DockPanel>
<ComboBox TabIndex="1" HorizontalAlignment="Stretch" VerticalAlignment="Center" SelectedValue="{Binding Path=Value, UpdateSourceTrigger=PropertyChanged}" SelectedValuePath="Value" ItemsSource="{Binding Path=FieldOptions}" Visibility="{Binding Path=FieldOptions, Converter={StaticResource EmptyCollectionIsInvisibleConverter}}" />
<TextBox TabIndex="2" Text="{Binding Value, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" HorizontalAlignment="Stretch" Visibility="{Binding Path=FieldOptions, Converter={StaticResource NonEmptyCollectionIsInvisibleConverter}}"/>
</DockPanel>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Header="Description" IsReadOnly="True" Width="*" >
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Description}" TextWrapping="Wrap" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
<DataGrid.RowDetailsTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Help}" />
</DataTemplate>
</DataGrid.RowDetailsTemplate>
</DataGrid>
</Grid>
</UserControl>

Answer 1

You can set the SelectionUnit to FullRow
SelectionUnit="FullRow"
or you can handle the selection event and set the visibility on event handling.
private void EntryGrid_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
{
foreach (var cell in e.AddedCells)
((DataGridRow)EntryGrid.ItemContainerGenerator.ContainerFromItem(cell.Item)).DetailsVisibility = System.Windows.Visibility.Visible;
foreach (var cell in e.RemovedCells)
((DataGridRow)EntryGrid.ItemContainerGenerator.ContainerFromItem(cell.Item)).DetailsVisibility = System.Windows.Visibility.Collapsed;
}
Insert disparaging remarks about the WPF DataGrid here.