Hierarchical selection

Both SelectionPrompt<T> and MultiSelectionPrompt<T> support nested choices via AddChoiceHierarchy. Parents toggle expansion when activated; leaves are the only thing the user can pick (by default).

When to use

• Region pickers (continent → country).
• Module pickers (group → module).
• Anywhere a flat list would be too long but the structure is naturally hierarchical.

Basic usage

var
  picker            : ISelectionPrompt<string>;
  americas, asia,
  oceania           : ISelectionItem<string>;
  region            : string;
begin
  picker := AnsiConsole.SelectionPrompt<string>
              .WithTitle('[yellow]Pick a region[/] [grey50](Enter to expand)[/]');

  oceania := picker.AddChoiceHierarchy('Oceania', '[bold]Oceania[/]');
  oceania.AddChild('au', 'Australia');
  oceania.AddChild('nz', 'New Zealand');
  oceania.AddChild('fi', 'Fiji');
  oceania.IsExpanded := True;     // pre-open this branch

  americas := picker.AddChoiceHierarchy('Americas', '[bold]Americas[/]');
  americas.AddChild('us', 'United States');
  americas.AddChild('ca', 'Canada');
  americas.AddChild('br', 'Brazil');

  asia := picker.AddChoiceHierarchy('Asia', '[bold]Asia[/]');
  asia.AddChild('cn', 'China');
  asia.AddChild('jp', 'Japan');
  asia.AddChild('kr', 'South Korea');

  region := picker.Show(AnsiConsole.Console);
  AnsiConsole.MarkupLine('You picked: [lime]%s[/]', [region]);
end;

Selection modes

TSelectionMode controls whether parents are themselves selectable:

Mode	Behaviour
Leaf (default)	Only leaves selectable. Enter on a parent toggles expansion.
Independent	Every node selectable in its own right. Useful when a parent has a meaningful "no specific child" value.

picker.WithSelectionMode(TSelectionMode.Independent);

Multi-selection variant

The same hierarchy API works on IMultiSelectionPrompt<T>:

picker := AnsiConsole.MultiSelectionPrompt<string>;
features := picker.AddChoiceHierarchy('frontend', 'Front-end');
features.AddChild('vue', 'Vue');
features.AddChild('react', 'React');

Use IMultiSelectionItem<T> instead of ISelectionItem<T> for the parent type when working with multi-selection (it adds Select / IsSelected).

Configuration

Beyond WithSelectionMode, the rest of the prompt configuration is inherited from SelectionPrompt<T> / MultiSelectionPrompt<T>: WithTitle, WithSearchEnabled, WithPageSize, WithCycle, etc.

API reference

• ISelectionPrompt<T>.AddChoiceHierarchy
• IMultiSelectionPrompt<T>.AddChoiceHierarchy
• ISelectionItem<T>
• IMultiSelectionItem<T>
• Demo: demos/snippets/Hierarchy.

See also

• Selection prompt.
• Multi-selection prompt.