# PopulateContextMenu

> Raised when a right click is handled on a node or on the background of the HierarchyView.

## Definition

* **Type:** Event
* **Namespace:** [Unity.Hierarchy.Editor](/engine/6000.7/script-reference/unity/hierarchy/editor.md)
* **Assembly:** UnityEditor

```csharp
public static event HierarchyWindow.PopulateContextMenuEventHandler PopulateContextMenu
```

### Remarks

This callback receives the [HierarchyViewItem](/engine/6000.7/script-reference/unity/hierarchy/hierarchyviewitem.md) to create the context menu for and the [DropdownMenu](/engine/6000.7/script-reference/unityengine/uielements/dropdownmenu.md) to populate. If the user right-clicks in empty space, the callback receives null for the view item.

The following example creates a context menu item that collapses all nodes in the Hierarchy window except the paths to the selected items. The action appears in the **Hierarchy Samples** submenu of the context menu. It uses `PopulateContextMenu` to add the context menu action.

### Examples

```csharp
using System;
using Unity.Hierarchy;
using Unity.Hierarchy.Editor;
using UnityEditor;
using UnityEngine.UIElements;

namespace Unity.HierarchySamples.Editor
{
    class CollapseOthers
    {
        [InitializeOnLoadMethod]
        static void Initialize()
        {
            HierarchyWindow.PopulateContextMenu += OnPopulateContextMenu;
        }

        static void OnPopulateContextMenu(HierarchyWindow window, HierarchyView view, HierarchyViewItem item, DropdownMenu menu)
        {
            menu.AppendAction("Hierarchy Samples/Collapse Others", a =>
            {
                // Capture selected and expanded nodes.
                int selectedAndExpandedCount = view.ViewModel.HasFlagsCount(HierarchyNodeFlags.Selected | HierarchyNodeFlags.Expanded);
                Span<HierarchyNode> expandedAndSelectedNodes = selectedAndExpandedCount < 16 ? stackalloc HierarchyNode[selectedAndExpandedCount] : new HierarchyNode[selectedAndExpandedCount];
                view.ViewModel.GetNodesWithFlags(HierarchyNodeFlags.Selected | HierarchyNodeFlags.Expanded, expandedAndSelectedNodes);

                // Create a flags change scope. This is an optimization to avoid triggering an update if no flags
                // actually changed after the operation.
                using (_ = new HierarchyViewModelFlagsChangeScope(view.ViewModel))
                {
                    // Collapse all nodes.
                    view.ViewModel.ClearFlags(HierarchyNodeFlags.Expanded);

                    // Expand parents of all selected nodes.
                    foreach (ref readonly var node in view.ViewModel.EnumerateNodesWithFlags(HierarchyNodeFlags.Selected))
                    {
                        var parent = view.ViewModel.GetParent(node);
                        if (parent == HierarchyNode.Null || parent == view.Source.Root) continue;
                        view.ViewModel.SetFlagsRecursive(parent, HierarchyNodeFlags.Expanded, HierarchyTraversalDirection.Parents);
                    }

                    // Expand all nodes that were previously expanded and selected.
                    view.Expand(expandedAndSelectedNodes);
                }

            }, _ => item == null || (view.ViewModel.HasFlagsCount(HierarchyNodeFlags.Selected) == 0)
                ? DropdownMenuAction.Status.Disabled
                : DropdownMenuAction.Status.Normal);
        }
    }
}
```