refactor(aria/tree): remove tree group wrapper

src/aria/combobox/combobox.spec.ts

@@ -4,7 +4,7 @@ import {By} from '@angular/platform-browser';
 import {Combobox, ComboboxInput, ComboboxPopup, ComboboxPopupContainer} from '../combobox';
 import {Listbox, Option} from '../listbox';
 import {runAccessibilityChecks} from '@angular/cdk/testing/private';
-import {Tree, TreeItem, TreeItemGroup, TreeItemGroupContent} from '../tree';
+import {Tree, TreeItem, TreeItemGroup} from '../tree';
 import {NgTemplateOutlet} from '@angular/common';
 
 describe('Combobox', () => {
@@ -1083,8 +1083,8 @@ class ComboboxListboxExample {
     </li>
 
     @if (node.children) {
-      <ul ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
-        <ng-template ngTreeItemGroupContent>
+      <ul role="group">
+        <ng-template ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
           <ng-template
             [ngTemplateOutlet]="treeNodes"
             [ngTemplateOutletContext]="{nodes: node.children, parent: group}"
@@ -1102,7 +1102,6 @@ class ComboboxListboxExample {
     Tree,
     TreeItem,
     TreeItemGroup,
-    TreeItemGroupContent,
     NgTemplateOutlet,
   ],
 })

src/aria/deferred-content/deferred-content.ts

@@ -42,19 +42,21 @@ export class DeferredContentAware {
  */
 @Directive()
 export class DeferredContent {
-  private readonly _deferredContentAware = inject(DeferredContentAware);
+  private readonly _deferredContentAware = inject(DeferredContentAware, {optional: true});
   private readonly _templateRef = inject(TemplateRef);
   private readonly _viewContainerRef = inject(ViewContainerRef);
   private _isRendered = false;
 
+  readonly deferredContentAware = signal(this._deferredContentAware);
+
   constructor() {
     afterRenderEffect(() => {
-      if (this._deferredContentAware.contentVisible()) {
+      if (this.deferredContentAware()?.contentVisible()) {
         if (this._isRendered) return;
         this._viewContainerRef.clear();
         this._viewContainerRef.createEmbeddedView(this._templateRef);
         this._isRendered = true;
-      } else if (!this._deferredContentAware.preserveContent()) {
+      } else if (!this.deferredContentAware()?.preserveContent()) {
         this._viewContainerRef.clear();
         this._isRendered = false;
       }

src/aria/tree/index.ts

@@ -6,4 +6,4 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-export {TreeItemGroup, TreeItemGroupContent, Tree, TreeItem} from './tree';
+export {TreeItemGroup, Tree, TreeItem} from './tree';

src/aria/tree/tree.spec.ts

@@ -4,7 +4,7 @@ import {ComponentFixture, TestBed} from '@angular/core/testing';
 import {By} from '@angular/platform-browser';
 import {Direction} from '@angular/cdk/bidi';
 import {provideFakeDirectionality, runAccessibilityChecks} from '@angular/cdk/testing/private';
-import {Tree, TreeItem, TreeItemGroup, TreeItemGroupContent} from './tree';
+import {Tree, TreeItem, TreeItemGroup} from './tree';
 
 interface ModifierKeys {
   ctrlKey?: boolean;
@@ -19,7 +19,6 @@ describe('Tree', () => {
   let treeElement: HTMLElement;
   let treeInstance: Tree<string>;
   let treeItemElements: HTMLElement[];
-  let treeItemGroupElements: HTMLElement[];
 
   const keydown = (key: string, modifierKeys: ModifierKeys = {}) => {
     const event = new KeyboardEvent('keydown', {key, bubbles: true, ...modifierKeys});
@@ -67,12 +66,10 @@ describe('Tree', () => {
   function defineTestVariables() {
     const treeDebugElement = fixture.debugElement.query(By.directive(Tree));
     const treeItemDebugElements = fixture.debugElement.queryAll(By.directive(TreeItem));
-    const treeItemGroupDebugElements = fixture.debugElement.queryAll(By.directive(TreeItemGroup));
 
     treeElement = treeDebugElement.nativeElement as HTMLElement;
     treeInstance = treeDebugElement.componentInstance as Tree<string>;
     treeItemElements = treeItemDebugElements.map(debugEl => debugEl.nativeElement);
-    treeItemGroupElements = treeItemGroupDebugElements.map(debugEl => debugEl.nativeElement);
   }
 
   function updateTree(
@@ -131,10 +128,6 @@ describe('Tree', () => {
     return treeItemElements.find(el => el.getAttribute('data-value') === String(value));
   }
 
-  function getTreeItemGroupElementByValue(value: string): HTMLElement | undefined {
-    return treeItemGroupElements.find(el => el.getAttribute('data-group-for') === String(value));
-  }
-
   function getFocusedTreeItemValue(): string | undefined {
     let item: HTMLElement | undefined;
     if (testComponent.focusMode() === 'roving') {
@@ -187,14 +180,6 @@ describe('Tree', () => {
         expect(getTreeItemElementByValue('blueberry')!.getAttribute('role')).toBe('treeitem');
       });
 
-      it('should correctly set the role attribute to "group" for TreeItemGroup', () => {
-        expandAll();
-
-        expect(getTreeItemGroupElementByValue('fruits')!.getAttribute('role')).toBe('group');
-        expect(getTreeItemGroupElementByValue('vegetables')!.getAttribute('role')).toBe('group');
-        expect(getTreeItemGroupElementByValue('berries')!.getAttribute('role')).toBe('group');
-      });
-
       it('should set aria-orientation to "vertical" by default', () => {
         expect(treeElement.getAttribute('aria-orientation')).toBe('vertical');
       });
@@ -262,12 +247,6 @@ describe('Tree', () => {
         expect(strawberry.getAttribute('aria-setsize')).toBe('2');
         expect(strawberry.getAttribute('aria-posinset')).toBe('1');
       });
-
-      it('should set aria-owns on expandable items pointing to their group id', () => {
-        const fruitsItem = getTreeItemElementByValue('fruits')!;
-        const group = getTreeItemGroupElementByValue('fruits')!;
-        expect(fruitsItem.getAttribute('aria-owns')).toBe(group!.id);
-      });
     });
 
     describe('custom configuration', () => {
@@ -1359,12 +1338,11 @@ interface TestTreeNode<V = string> {
       >
         {{ node.label }}
         @if (node.children !== undefined && node.children!.length > 0) {
-          <ul
-            ngTreeItemGroup
-            [ownedBy]="treeItem"
-            [attr.data-group-for]="node.value"
-            #group="ngTreeItemGroup">
-            <ng-template ngTreeItemGroupContent>
+          <ul role="group">
+            <ng-template
+              ngTreeItemGroup
+              [ownedBy]="treeItem"
+              #group="ngTreeItemGroup">
               @for (node of node.children; track node.value) {
                 <ng-template [ngTemplateOutlet]="nodeTemplate" [ngTemplateOutletContext]="{ node: node, parent: group }" />
               }
@@ -1374,7 +1352,7 @@ interface TestTreeNode<V = string> {
       </li>
     </ng-template>
   `,
-  imports: [Tree, TreeItem, TreeItemGroup, TreeItemGroupContent, NgTemplateOutlet],
+  imports: [Tree, TreeItem, TreeItemGroup, NgTemplateOutlet],
 })
 class TestTreeComponent {
   nodes = signal<TestTreeNode[]>([

src/aria/tree/tree.ts

@@ -218,13 +218,12 @@ export class Tree<V> {
     '[attr.aria-current]': 'pattern.current()',
     '[attr.aria-disabled]': 'pattern.disabled()',
     '[attr.aria-level]': 'pattern.level()',
-    '[attr.aria-owns]': 'ownsId()',
     '[attr.aria-setsize]': 'pattern.setsize()',
     '[attr.aria-posinset]': 'pattern.posinset()',
     '[attr.tabindex]': 'pattern.tabindex()',
   },
 })
-export class TreeItem<V> implements OnInit, OnDestroy, HasElement {
+export class TreeItem<V> extends DeferredContentAware implements OnInit, OnDestroy, HasElement {
   /** A reference to the tree item element. */
   private readonly _elementRef = inject(ElementRef);
 
@@ -234,9 +233,6 @@ export class TreeItem<V> implements OnInit, OnDestroy, HasElement {
   /** The owned tree item group. */
   private readonly _group = signal<TreeItemGroup<V> | undefined>(undefined);
 
-  /** The id of the owned group. */
-  readonly ownsId = computed(() => this._group()?.id);
-
   /** The host native element. */
   readonly element = computed(() => this._elementRef.nativeElement);
 
@@ -267,9 +263,13 @@ export class TreeItem<V> implements OnInit, OnDestroy, HasElement {
   pattern: TreeItemPattern<V>;
 
   constructor() {
-    // Updates the visibility of the owned group.
+    super();
+    this.preserveContent.set(true);
+    // Connect the group's hidden state to the DeferredContentAware's visibility.
     afterRenderEffect(() => {
-      this._group()?.visible.set(this.pattern.expanded());
+      this.tree().pattern instanceof ComboboxTreePattern
+        ? this.contentVisible.set(true)
+        : this.contentVisible.set(this.pattern.expanded());
     });
   }
 
@@ -289,12 +289,7 @@ export class TreeItem<V> implements OnInit, OnDestroy, HasElement {
       id: () => this._id,
       tree: treePattern,
       parent: parentPattern,
-      children: computed(
-        () =>
-          this._group()
-            ?.children()
-            .map(item => (item as TreeItem<V>).pattern) ?? [],
-      ),
+      children: computed(() => this._group()?.children() ?? []),
       hasChildren: computed(() => !!this._group()),
     });
   }
@@ -314,60 +309,30 @@ export class TreeItem<V> implements OnInit, OnDestroy, HasElement {
 }
 
 /**
- * Container that designates content as a group.
+ * Contains children tree itmes.
  */
 @Directive({
-  selector: '[ngTreeItemGroup]',
+  selector: 'ng-template[ngTreeItemGroup]',
   exportAs: 'ngTreeItemGroup',
-  hostDirectives: [
-    {
-      directive: DeferredContentAware,
-      inputs: ['preserveContent'],
-    },
-  ],
-  host: {
-    'class': 'ng-treeitem-group',
-    'role': 'group',
-    '[id]': 'id',
-    '[attr.inert]': 'visible() ? null : true',
-  },
+  hostDirectives: [DeferredContent],
 })
-export class TreeItemGroup<V> implements OnInit, OnDestroy, HasElement {
-  /** A reference to the group element. */
-  private readonly _elementRef = inject(ElementRef);
-
-  /** The DeferredContentAware host directive. */
-  private readonly _deferredContentAware = inject(DeferredContentAware);
+export class TreeItemGroup<V> implements OnInit, OnDestroy {
+  /** The DeferredContent host directive. */
+  private readonly _deferredContent = inject(DeferredContent);
 
   /** All groupable items that are descendants of the group. */
   private readonly _unorderedItems = signal(new Set<TreeItem<V>>());
 
-  /** The host native element. */
-  readonly element = computed(() => this._elementRef.nativeElement);
-
-  /** Unique ID for the group. */
-  readonly id = inject(_IdGenerator).getId('ng-tree-group-');
-
-  /** Whether the group is visible. */
-  readonly visible = signal(true);
-
   /** Child items within this group. */
-  readonly children = computed(() => [...this._unorderedItems()].sort(sortDirectives));
+  readonly children = computed<TreeItemPattern<V>[]>(() =>
+    [...this._unorderedItems()].sort(sortDirectives).map(c => c.pattern),
+  );
 
   /** Tree item that owns the group. */
   readonly ownedBy = input.required<TreeItem<V>>();
 
-  constructor() {
-    this._deferredContentAware.preserveContent.set(true);
-    // Connect the group's hidden state to the DeferredContentAware's visibility.
-    afterRenderEffect(() => {
-      this.ownedBy().tree().pattern instanceof ComboboxTreePattern
-        ? this._deferredContentAware.contentVisible.set(true)
-        : this._deferredContentAware.contentVisible.set(this.visible());
-    });
-  }
-
   ngOnInit() {
+    this._deferredContent.deferredContentAware.set(this.ownedBy());
     this.ownedBy().register(this);
   }
 
@@ -385,13 +350,3 @@ export class TreeItemGroup<V> implements OnInit, OnDestroy, HasElement {
     this._unorderedItems.set(new Set(this._unorderedItems()));
   }
 }
-
-/**
- * A structural directive that marks the `ng-template` to be used as the content
- * for a `TreeItemGroup`. This content can be lazily loaded.
- */
-@Directive({
-  selector: 'ng-template[ngTreeItemGroupContent]',
-  hostDirectives: [DeferredContent],
-})
-export class TreeItemGroupContent {}

src/components-examples/aria/combobox/combobox-tree-auto-select/combobox-tree-auto-select-example.html

@@ -49,8 +49,8 @@
     </li>
 
     @if (node.children) {
-      <ul ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
-        <ng-template ngTreeItemGroupContent>
+      <ul role="group">
+        <ng-template  ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
           <ng-template
             [ngTemplateOutlet]="treeNodes"
             [ngTemplateOutletContext]="{nodes: node.children, parent: group}"

src/components-examples/aria/combobox/combobox-tree-auto-select/combobox-tree-auto-select-example.ts

@@ -12,7 +12,7 @@ import {
   ComboboxPopup,
   ComboboxPopupContainer,
 } from '@angular/aria/combobox';
-import {Tree, TreeItem, TreeItemGroup, TreeItemGroupContent} from '@angular/aria/tree';
+import {Tree, TreeItem, TreeItemGroup} from '@angular/aria/tree';
 import {
   afterRenderEffect,
   ChangeDetectionStrategy,
@@ -38,7 +38,6 @@ import {NgTemplateOutlet} from '@angular/common';
     Tree,
     TreeItem,
     TreeItemGroup,
-    TreeItemGroupContent,
     NgTemplateOutlet,
   ],
   changeDetection: ChangeDetectionStrategy.OnPush,

src/components-examples/aria/combobox/combobox-tree-highlight/combobox-tree-highlight-example.html

@@ -49,8 +49,8 @@
     </li>
 
     @if (node.children) {
-      <ul ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
-        <ng-template ngTreeItemGroupContent>
+      <ul role="group">
+        <ng-template ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
           <ng-template
             [ngTemplateOutlet]="treeNodes"
             [ngTemplateOutletContext]="{nodes: node.children, parent: group}"

src/components-examples/aria/combobox/combobox-tree-highlight/combobox-tree-highlight-example.ts

@@ -12,7 +12,7 @@ import {
   ComboboxPopup,
   ComboboxPopupContainer,
 } from '@angular/aria/combobox';
-import {Tree, TreeItem, TreeItemGroup, TreeItemGroupContent} from '@angular/aria/tree';
+import {Tree, TreeItem, TreeItemGroup} from '@angular/aria/tree';
 import {
   afterRenderEffect,
   ChangeDetectionStrategy,
@@ -38,7 +38,6 @@ import {NgTemplateOutlet} from '@angular/common';
     Tree,
     TreeItem,
     TreeItemGroup,
-    TreeItemGroupContent,
     NgTemplateOutlet,
   ],
   changeDetection: ChangeDetectionStrategy.OnPush,

src/components-examples/aria/combobox/combobox-tree-manual/combobox-tree-manual-example.html

@@ -49,8 +49,8 @@
     </li>
 
     @if (node.children) {
-      <ul ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
-        <ng-template ngTreeItemGroupContent>
+      <ul role="group">
+        <ng-template ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
           <ng-template
             [ngTemplateOutlet]="treeNodes"
             [ngTemplateOutletContext]="{nodes: node.children, parent: group}"

src/components-examples/aria/combobox/combobox-tree-manual/combobox-tree-manual-example.ts

@@ -12,7 +12,7 @@ import {
   ComboboxPopup,
   ComboboxPopupContainer,
 } from '@angular/aria/combobox';
-import {Tree, TreeItem, TreeItemGroup, TreeItemGroupContent} from '@angular/aria/tree';
+import {Tree, TreeItem, TreeItemGroup} from '@angular/aria/tree';
 import {
   afterRenderEffect,
   ChangeDetectionStrategy,
@@ -38,7 +38,6 @@ import {NgTemplateOutlet} from '@angular/common';
     Tree,
     TreeItem,
     TreeItemGroup,
-    TreeItemGroupContent,
     NgTemplateOutlet,
   ],
   changeDetection: ChangeDetectionStrategy.OnPush,

src/components-examples/aria/tree/tree-active-descendant/tree-active-descendant-example.html

@@ -23,8 +23,8 @@
   </li>
 
   @if (node.children) {
-  <ul ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
-    <ng-template ngTreeItemGroupContent>
+  <ul role="group">
+    <ng-template ngTreeItemGroup [ownedBy]="treeItem" #group="ngTreeItemGroup">
       <ng-template
         [ngTemplateOutlet]="treeNodes"
         [ngTemplateOutletContext]="{nodes: node.children, parent: group}"