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Expanding and Collapsing Rows

Basic Expand/Collapse Operations​

For hierarchical TreeDataGrids, you can programmatically expand or collapse rows:

var Source = new HierarchicalTreeDataGridSource<Person>(_people)
{
    Columns = { /* columns */ }
};

// Expand a specific node by index path
Source.Expand(new IndexPath(0));  // Expand first root item

// Collapse a node
Source.Collapse(new IndexPath(0));
info

For more information about IndexPath see Selection

Expand All / Collapse All​

The source provides built-in methods for expanding/collapsing all rows:

// Expand all rows in the tree
Source.ExpandAll();

// Collapse all rows in the tree
Source.CollapseAll();

Expand or Collapse Based on Condition​

You can expand/collapse rows based on a condition:

// Expand all rows where Person.Age > 18
Source.ExpandCollapseRecursive(person => person.Age > 18);

// Collapse all rows
Source.ExpandCollapseRecursive(_ => false);

Responding to Expand/Collapse Events​

You can handle expand and collapse events to load data on demand or perform other actions:

Source.RowExpanding += (sender, e) =>
{
    var person = e.Row.Model;
    var indexPath = e.Row.ModelIndexPath;
    Debug.WriteLine($"Expanding: {person.Name} at {indexPath}");
};

Source.RowExpanded += (sender, e) =>
{
    var person = e.Row.Model;
    var indexPath = e.Row.ModelIndexPath;
    Debug.WriteLine($"Expanded: {person.Name} at {indexPath}");
};

Source.RowCollapsing += (sender, e) =>
{
    var person = e.Row.Model;
    Debug.WriteLine($"Collapsing: {person.Name}");
};

Source.RowCollapsed += (sender, e) =>
{
    var person = e.Row.Model;
    Debug.WriteLine($"Collapsed: {person.Name}");
};