TreeListView/DataGrid in .NET 5 - datagrid

Question

I am trying to implement a TreeListView/DataGrid in .Net 5.
What I need is extendible columns (meaning I can adapt the width in the GUI) and also fold-out rows (like in a tree, each parent and subnode should have data in multiple columns).
For example like this:
What I tried so far:
TreeView: Doesn't have extendible columns
DataGrid and grouping: The header=parent does not have columns like its childrows.
I tried many useful packages like "objectListView", but they do not run on .Net5.
I downloaded DotNetProjects.Extended.Wpf.Toolkit, but don't find a good documentation on how to use it.
Which would be the best way to get ahead with this?
Thanks for any hints!

Answer 1

I ended up writing my own expander button.
It's just a prototype, intended to be used only with one sublevel and without column-sorting.
But it can be extended for other use cases. Hope it might help someone who bumps over the same issue.
I'm still looking forward to getting any hints or ideas for improvement.
thx!
Example outcome:
View (XAML)
<DataGrid Name="dgUsers" Grid.Row="0" Visibility="Visible" AutoGenerateColumns="False" ItemsSource="{Binding Users}"
CanUserAddRows="False" CanUserDeleteRows="False" CanUserSortColumns="False">
<DataGrid.Columns>
<DataGridTemplateColumn Header="Name">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<StackPanel>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Name="Expander" Width="Auto"></ColumnDefinition>
<ColumnDefinition Name="Content" Width="Auto"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Grid.Column="0" HorizontalAlignment="Left" Background="GhostWhite" BorderBrush="GhostWhite"
Visibility="{Binding ExpanderVisibility}"
Command="{Binding ExpandCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type DataGrid}}}"
Content="{Binding ExpanderSign}">
</Button>
<CheckBox Grid.Column="1" Margin="{Binding CheckboxMargin}"/>
<TextBlock Grid.Column="1" Text="{Binding Name}" Margin="{Binding JobNameMargin}"/>
</Grid>
</StackPanel>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Header="Birthday" Binding="{Binding Birthday}" />
</DataGrid.Columns>
</DataGrid>
ViewModel (C#):
public class JobViewModel : BindableBase
{
private ObservableCollection<User> _users = new ObservableCollection<User>();
private static string _isExpandedSign = "^";
private static string _expandableSign = ">";
public JobViewModel()
{
var cori = ((new User() { Name = "Cori", Birthday = new DateTime(1982, 8, 10), ExpanderVisibility = "Hidden" }));
var penny = ((new User() { Name = "Penny", Birthday = new DateTime(1976, 7, 31), ExpanderVisibility = "Hidden" }));
var john = ((new User() { Id = 10, Name = "John Doe", Birthday = new DateTime(1971, 7, 23) } ));
var samy = ((new User() { Id = 20, Name = "Sammy Doe", Birthday = new DateTime(1991, 9, 2) }));
var jane = ((new User() { Id = 30, Name = "Jane Doe", Birthday = new DateTime(1974, 1, 17) }));
var anny = ((new User() { Id = 40, Name = "Anny Doe", Birthday = new DateTime(1931, 1, 26) }));
john.AddChild(cori);
john.AddChild(penny);
jane.AddChild(cori);
jane.AddChild(penny);
anny.AddChild(cori);
anny.AddChild(penny);
_users.Add(john);
_users.Add(samy);
_users.Add(jane);
_users.Add(anny);
}
public class User : BindableBase
{
public int Id { get; set; }
public string ExpanderVisibility { get; set; }
public string CheckboxMargin { get; set; }
public string JobNameMargin { get; set; }
public bool IsExpanded { get; set; }
public string Name { get; set; }
public DateTime Birthday { get; set; }
public List<User> Children { get; set; }
public bool IsChild { get; set; }
public ICommand ExpandCommand { get; private set; }
public bool HasChildren()
{
return true;
}
public User(){
ExpandCommand = new DelegateCommand<DataGrid>(ExecuteExpandCommand);
ExpanderVisibility = "Hidden";
CheckboxMargin = "3,0,0,0";
JobNameMargin = "25,0,5,0";
Children = new List<User>();
}
public string ExpanderSign
{
get {
if (this.IsExpanded) return (_isExpandedSign);
else return (_expandableSign);
}
}
public void AddChild(User child)
{
child.CheckboxMargin = "23,0,0,0";
child.JobNameMargin = "45,0,5,0";
child.IsChild = true;
Children.Add(child);
ExpanderVisibility = "Visible";
}
private void ExecuteExpandCommand(DataGrid dg)
{
ObservableCollection<User> items = (ObservableCollection<User>)dg.ItemsSource;
int parentIndex=items.IndexOf(this);
if (!IsExpanded)
{
//expand
for (int i = 0; i < Children.Count; ++i)
{
items.Insert(parentIndex + 1 + i, Children.ElementAt(i));
}
}
else
{
int childrenCount = Children.Count;
for (int i=0; i< childrenCount; ++i)
{
if(parentIndex + 1 < items.Count && items.ElementAt(parentIndex + 1).IsChild) //just to be sure
{
items.RemoveAt(parentIndex + 1);
}
}
}
IsExpanded = !IsExpanded;
RaisePropertyChanged("ExpanderSign");
}
}
public ObservableCollection<User> Users
{
get { return _users; }
set { _users = value; }
}
}