Umbraco Tree

What is it?

A tree in Umbraco is a hierarchical structure of nodes registered in the Backoffice extension registry. Trees display organized content hierarchies and can be rendered anywhere in the Backoffice using the <umb-tree /> element. They require a data source implementation to fetch root items, children, and ancestors.

Documentation

Always fetch the latest docs before implementing:

Main docs: https://docs.umbraco.com/umbraco-cms/customizing/extending-overview/extension-types/tree
Sections & Trees: https://docs.umbraco.com/umbraco-cms/customizing/overview
Foundation: https://docs.umbraco.com/umbraco-cms/customizing/foundation
Extension Registry: https://docs.umbraco.com/umbraco-cms/customizing/extending-overview/extension-registry

CRITICAL: Tree + Workspace Integration

Trees and workspaces are tightly coupled. When using kind: 'default' tree items:

Tree items REQUIRE workspaces - Clicking a tree item navigates to a workspace for that entity type. Without a workspace registered for the entityType, clicking causes "forever loading"
Workspaces must be kind: 'routable' - For proper tree item selection state and navigation between items of the same type, use kind: 'routable' workspaces (not kind: 'default')
Entity types link trees to workspaces - The entityType in your tree item data must match the entityType in your workspace manifest

When implementing trees with clickable items, also reference the umbraco-workspace skill.

File Structure

Modern trees use 2-3 files:

my-tree/
├── manifest.ts          # Registers repository and tree
├── tree.repository.ts   # Repository + inline data source
└── types.ts             # Type definitions (optional)

Reference Example

The Umbraco source includes a working example:

Location: /Umbraco-CMS/src/Umbraco.Web.UI.Client/examples/tree/

This example demonstrates a complete custom tree with data source, repository, and menu integration. Study this for production patterns.

Related Foundation Skills

If you need to explain these foundational concepts when implementing trees, reference these skills:

Repository Pattern: When implementing tree data sources, repositories, data fetching, or CRUD operations
- Reference skill: umbraco-repository-pattern
Context API: When implementing repository contexts or explaining how repositories connect to UI components
- Reference skill: umbraco-context-api
State Management: When implementing reactive tree updates, observables, or managing tree state
- Reference skill: umbraco-state-management

Workflow

Fetch docs - Use WebFetch on the URLs above
Ask questions - What data will the tree display? What repository will provide the data? Where will it appear? Will tree items be clickable?
Generate files - Create minimal files based on latest docs
- ✅ Create: manifest.ts, tree.repository.ts (with inline data source)
- ❌ Don't create: tree.store.ts (deprecated), separate tree.data-source.ts (can inline)
- Use the inline data source pattern shown in examples below
If clickable - Also create routable workspaces for each entity type (reference umbraco-workspace skill)
Explain - Show what was created and how to test

Key Configuration Options

hideTreeRoot on MenuItem (NOT on Tree)

To show tree items at root level (without a parent folder), use hideTreeRoot: true on the menuItem manifest:

// CORRECT - hideTreeRoot on menuItem
{
  type: 'menuItem',
  kind: 'tree',
  alias: 'My.MenuItem.Tree',
  meta: {
    treeAlias: 'My.Tree',
    menus: ['My.Menu'],
    hideTreeRoot: true,  // Shows items at root level
  },
}

// WRONG - hideTreeRoot on tree (has no effect)
{
  type: 'tree',
  meta: {
    hideTreeRoot: true,  // This does nothing!
  },
}

Minimal Examples

Tree Manifest

export const manifests: UmbExtensionManifest[] = [
  // Repository
  {
    type: 'repository',
    alias: 'My.Tree.Repository',
    name: 'My Tree Repository',
    api: () => import('./tree.repository.js'),
  },
  // Tree
  {
    type: 'tree',
    kind: 'default',
    alias: 'My.Tree',
    name: 'My Tree',
    meta: {
      repositoryAlias: 'My.Tree.Repository',
    },
  },
  // Tree Items - use kind: 'default' when workspaces exist
  {
    type: 'treeItem',
    kind: 'default',
    alias: 'My.TreeItem',
    name: 'My Tree Item',
    forEntityTypes: ['my-entity'],
  },
  // MenuItem - hideTreeRoot here
  {
    type: 'menuItem',
    kind: 'tree',
    alias: 'My.MenuItem.Tree',
    meta: {
      treeAlias: 'My.Tree',
      menus: ['My.Menu'],
      hideTreeRoot: true,
    },
  },
];

Repository with Inline Data Source (tree.repository.ts)

Modern simplified pattern - everything in one file:

import { UmbTreeRepositoryBase, UmbTreeServerDataSourceBase } from '@umbraco-cms/backoffice/tree';
import type { UmbControllerHost } from '@umbraco-cms/backoffice/controller-api';
import type { UmbApi } from '@umbraco-cms/backoffice/extension-api';
import type { MyTreeItemModel, MyTreeRootModel } from './types.js';
import { MY_ROOT_ENTITY_TYPE, MY_ENTITY_TYPE } from './entity.js';

// Data source as simple class using helper base
class MyTreeDataSource extends UmbTreeServerDataSourceBase<any, MyTreeItemModel> {
  constructor(host: UmbControllerHost) {
    super(host, {
      getRootItems: async (args) => {
        // Fetch from API or return mock data
        const items: MyTreeItemModel[] = [
          {
            unique: 'item-1',
            parent: { unique: null, entityType: MY_ROOT_ENTITY_TYPE },
            entityType: MY_ENTITY_TYPE,
            name: 'Item 1',
            hasChildren: false,
            isFolder: false,
            icon: 'icon-document',
          },
        ];
        return { data: { items, total: items.length } };
      },
      getChildrenOf: async (args) => {
        // Return children for parent
        return { data: { items: [], total: 0 } };
      },
      getAncestorsOf: async (args) => {
        // Return ancestor path
        return { data: [] };
      },
      mapper: (item: any) => item, // Identity mapper for this example
    });
  }
}

// Repository
export class MyTreeRepository
  extends UmbTreeRepositoryBase<MyTreeItemModel, MyTreeRootModel>
  implements UmbApi
{
  constructor(host: UmbControllerHost) {
    super(host, MyTreeDataSource);
  }

  async requestTreeRoot() {
    const data: MyTreeRootModel = {
      unique: null,
      entityType: MY_ROOT_ENTITY_TYPE,
      name: 'My Tree',
      hasChildren: true,
      isFolder: true,
    };
    return { data };
  }
}

export { MyTreeRepository as api };

Why this is simpler:

✅ One file instead of two
✅ Uses UmbTreeServerDataSourceBase helper (pass functions, not methods)
✅ Data fetching logic inline (easier to understand)
✅ No separate data source file to maintain

For complex trees with API calls, you can still separate into different files, but it's not required.

That's it! Always fetch fresh docs, keep examples minimal, generate complete working code.

umbraco-tree