I need the Expand / Collapse for RowDetailsTemplate

I have a DataGrid. It has DataGrid.RowDetailsTemplate. When a button is clicked it should Expand / Collapse; how would I do that?

<Custom:DataGrid RowDetailsVisibilityMode="VisibleWhenSelected" SelectionMode="Extended" CanUserAddRows="False" CanUserDeleteRows="False" CanUserResizeRows="False" CanUserSortColumns="False">
    <Custom:DataGrid.RowDetailsTemplate>
        <DataTemplate>
            <Custom:DataGrid>
                <Custom:DataGrid.Columns>
                    <Custom:DataGridTextColumn Binding="{Binding idClient, Mode=Default}" Header="Ид" IsReadOnly="True"/>
                    <Custom:DataGridTextColumn Binding="{Binding name_client, Mode=Default}"  Header="Имя" IsReadOnly="True"/>
                </Custom:DataGrid.Columns>
            </Custom:DataGrid>
        </DataTemplate>
    </Custom:DataGrid.RowDetailsTemplate>
    <Custom:DataGrid.Columns>
        <Custom:DataGridTemplateColumn>
            <Custom:DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Expander IsExpanded="True"/>
                </DataTemplate>
            </Custom:DataGridTemplateColumn.CellTemplate>
        </Custom:DataGridTemplateColumn>
        <Custom:DataGridTextColumn Binding="{Binding idPartner, Mode=Default}" Header="Ид" IsReadOnly="True"/>
        <Custom:DataGridTextColumn Binding="{Binding name_partner, Mode=Default}"  Header="Имя" IsRea开发者_运维百科dOnly="True"/>
    </Custom:DataGrid.Columns>
</Custom:DataGrid>

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Check this ...

Adding a Button to a WPF DataGrid

OR

XAML :

<DataGrid Name="dg1" AutoGenerateColumns="False" SelectionMode="Single" CanUserAddRows="false" CanUserDeleteRows="False" SelectionUnit="FullRow" >
    <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
            <Setter Property="BorderThickness" Value="0"/>
        </Style>
    </DataGrid.CellStyle>

    <DataGrid.RowHeaderTemplate>
        <DataTemplate>
            <Expander Expanded="Expander_Expanded" Collapsed="Expander_Collapsed">

            </Expander>
        </DataTemplate>
    </DataGrid.RowHeaderTemplate>

    <DataGrid.Columns>
        <DataGridTextColumn Header="Name" IsReadOnly="True" Width="100" Binding="{Binding Name}" />
        <DataGridTextColumn Header="Title" IsReadOnly="True" Width="100" Binding="{Binding Title}" />
        <DataGridTextColumn Header="Job" IsReadOnly="True" Width="100" Binding="{Binding Job}" />
    </DataGrid.Columns>

    <DataGrid.RowDetailsTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Isi, Converter={StaticResource ResourceKey=isiTextConverter}}" Margin="10,5,0,0" />
        </DataTemplate>
    </DataGrid.RowDetailsTemplate>
</DataGrid>

MainWindow.xaml.cs

private void Expander_Expanded(object sender, RoutedEventArgs e)
{
    for (var vis = sender as Visual; vis != null; vis = VisualTreeHelper.GetParent(vis) as Visual)
    if (vis is DataGridRow)
    {
        var row = (DataGridRow)vis;
        row.DetailsVisibility = row.DetailsVisibility == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;
        break;
    }
}

private void Expander_Collapsed(object sender, RoutedEventArgs e)
{
    for (var vis = sender as Visual; vis != null; vis = VisualTreeHelper.GetParent(vis) as Visual)
        if (vis is DataGridRow)
        {
            var row = (DataGridRow)vis;
            row.DetailsVisibility = row.DetailsVisibility == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;
            break;
        }
}

Output

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Selecting a Row on the Grid should expand the Row using the RowDetailsTemplate to display the content. This makes that Row the Selected Row and sets the value of the DataGrid's SelectedIndex Property.

To collapse the Row set the DataGrid's SelectedIndex Property to -1.

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Include Collapsed and expanded events as below

   <Custom:DataGridTemplateColumn>
   <Custom:DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
                <Expander Collapsed="exp_Collapsed" Expanded="exp_Expanded"/>
            </DataTemplate>
        </Custom:DataGridTemplateColumn.CellTemplate>
    </Custom:DataGridTemplateColumn>

In the code behind

 private void exp_Collapsed(object sender, RoutedEventArgs e)
        {
            this.dataGrid1.RowDetailsVisibilityMode = DataGridRowDetailsVisibilityMode.Collapsed;
        }

        private void exp_Expanded(object sender, RoutedEventArgs e)
        {
            this.dataGrid1.RowDetailsVisibilityMode = DataGridRowDetailsVisibilityMode.VisibleWhenSelected;
        }

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I have improved the previous answer :

Instead of using DataGrid.RowHeaderTemplate use DataGridTemplateColumn as below:

<DataGridTemplateColumn>
   <DataGridTemplateColumn.CellTemplate>
          <DataTemplate>
                <Expander Expanded="Expander_OnExpanded"     Collapsed="Expander_OnCollapsed">
                </Expander>
           </DataTemplate>
   </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

Benifit is you need not to re position your mouse after clicking expander button.

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Instead of walking the tree to find the datagrid row from the expander, use the static method GetRowContainingElement which is found on DataGridRow. Such as:

private void Expander_Process(object sender, RoutedEventArgs e)
{
    if (sender is Expander expander)
    {
        var row = DataGridRow.GetRowContainingElement(expander);

        row.DetailsVisibility = expander.IsExpanded ? Visibility.Visible 
                                                    : Visibility.Collapsed;
    }
}

Then the expander has only one method call for each of the events:

 <Expander Expanded="Expander_Process"  Collapsed="Expander_Process" />