Fixed #15579 - TreeSelect | Add lazy support

src/app/components/treeselect/treeselect.ts

@@ -170,6 +170,7 @@ export const TREESELECT_VALUE_ACCESSOR: any = {
                                 [virtualScrollItemSize]="virtualScrollItemSize"
                                 [virtualScrollOptions]="virtualScrollOptions"
                                 [_templateMap]="templateMap"
+                                [loading]="loading"
                             >
                                 <ng-container *ngIf="emptyTemplate">
                                     <ng-template pTemplate="empty">
@@ -425,6 +426,11 @@ export class TreeSelect implements AfterContentInit {
         this._hideTransitionOptions = val;
         console.warn('The hideTransitionOptions property is deprecated since v14.2.0, use overlayOptions property instead.');
     }
+    /**
+     * Displays a loader to indicate data load is in progress.
+     * @group Props
+     */
+    @Input({ transform: booleanAttribute }) loading: boolean | undefined;
     /**
      * Callback to invoke when a node is expanded.
      * @param {TreeSelectNodeExpandEvent} event - Custom node expand event.

src/app/showcase/doc/treeselect/lazydoc.ts

@@ -0,0 +1,228 @@
+import { ChangeDetectorRef, Component } from '@angular/core';
+import { Code } from '@domain/code';
+import { NodeService } from '@service/nodeservice';
+import { TreeNode } from 'primeng/api';
+
+@Component({
+    selector: 'lazy-doc',
+    template: `
+        <app-docsectiontext>
+            <p>Lazy loading is useful when dealing with huge datasets, in this example nodes are dynamically loaded on demand using <i>loading</i> property and <i>onNodeExpand</i> method.</p>
+        </app-docsectiontext>
+        <div class="card flex justify-content-center">
+            <p-treeSelect
+                class="w-full"
+                containerStyleClass="w-full"
+                [(ngModel)]="selectedNodes"
+                [loading]="loading"
+                (onNodeExpand)="onNodeExpand($event)"
+                [options]="nodes"
+                display="chip"
+                [metaKeySelection]="false"
+                selectionMode="checkbox"
+                placeholder="Select Item"
+                [loading]="loading"
+            />
+        </div>
+        <app-code [code]="code" selector="tree-select-basic-demo"></app-code>
+    `
+})
+export class LazyDoc {
+    selectedNodes: TreeNode[] = [];
+
+    nodes!: TreeNode[];
+
+    loading: boolean = false;
+
+    constructor(private cd: ChangeDetectorRef) {}
+
+    ngOnInit() {
+        this.loading = true;
+
+        setTimeout(() => {
+            this.nodes = this.initiateNodes();
+            this.loading = false;
+            this.cd.markForCheck();
+        }, 2000);
+    }
+
+    initiateNodes(): TreeNode[] {
+        return [
+            {
+                key: '0',
+                label: 'Node 0',
+                leaf: false
+            },
+            {
+                key: '1',
+                label: 'Node 1',
+                leaf: false
+            },
+            {
+                key: '2',
+                label: 'Node 2',
+                leaf: false
+            }
+        ];
+    }
+
+    onNodeExpand(event: any) {
+        if (!event.node.children) {
+            this.loading = true;
+
+            setTimeout(() => {
+                let _node = { ...event.node };
+                _node.children = [];
+
+                for (let i = 0; i < 1500; i++) {
+                    _node.children.push({
+                        key: event.node.key + '-' + i,
+                        label: 'Lazy ' + event.node.label + '-' + i
+                    });
+                }
+
+                this.nodes[parseInt(event.node.key, 10)] = _node;
+
+                this.loading = false;
+                this.cd.markForCheck();
+            }, 500);
+        }
+    }
+
+    code: Code = {
+        basic: `<p-treeSelect
+    class="w-full"
+    containerStyleClass="w-full"
+    [(ngModel)]="selectedNodes"
+    [loading]="loading"
+    (onNodeExpand)="onNodeExpand($event)"
+    [options]="nodes"
+    display="chip"
+    [metaKeySelection]="false"
+    selectionMode="checkbox"
+    placeholder="Select Item"
+    [loading]="loading"
+/>`,
+
+        html: `<div class="card flex justify-content-center">
+    <p-treeSelect
+        class="w-full"
+        containerStyleClass="w-full"
+        [(ngModel)]="selectedNodes"
+        [loading]="loading"
+        (onNodeExpand)="onNodeExpand($event)"
+        [options]="nodes"
+        display="chip"
+        [metaKeySelection]="false"
+        selectionMode="checkbox"
+        placeholder="Select Item"
+        [loading]="loading"
+    />
+</div>`,
+
+        typescript: `import { Component } from '@angular/core';
+import { NodeService } from '@service/nodeservice';
+import { FormsModule } from '@angular/forms';
+import { TreeSelectModule } from 'primeng/treeselect';
+
+@Component({
+    selector: 'tree-select-lazy-demo',
+    templateUrl: './tree-select-lazy-demo.html',
+    standalone: true,
+    imports: [FormsModule, TreeSelectModule]
+  })
+export class TreeSelectLazyDemo {
+    selectedNodes: TreeNode[] = [];
+
+    nodes!: TreeNode[];
+
+    loading: boolean = false;
+
+    constructor(private cd: ChangeDetectorRef) {}
+
+    ngOnInit() {
+        this.loading = true;
+
+        setTimeout(() => {
+            this.nodes = this.initiateNodes();
+            this.loading = false;
+            this.cd.markForCheck();
+        }, 2000);
+    }
+
+    initiateNodes(): TreeNode[] {
+        return [
+            {
+                key: '0',
+                label: 'Node 0',
+                leaf: false
+            },
+            {
+                key: '1',
+                label: 'Node 1',
+                leaf: false
+            },
+            {
+                key: '2',
+                label: 'Node 2',
+                leaf: false
+            }
+        ];
+    }
+
+    onNodeExpand(event: any) {
+        if (!event.node.children) {
+            this.loading = true;
+
+            setTimeout(() => {
+                let _node = { ...event.node };
+                _node.children = [];
+
+                for (let i = 0; i < 150; i++) {
+                    _node.children.push({
+                        key: event.node.key + '-' + i,
+                        label: 'Lazy ' + event.node.label + '-' + i
+                    });
+                }
+
+                this.nodes[parseInt(event.node.key, 10)] = _node;
+
+                this.loading = false;
+                this.cd.markForCheck();
+            }, 500);
+        }
+    }
+}`,
+
+        service: ['NodeService'],
+
+        data: `
+    /* NodeService */
+{
+    key: '0',
+    label: 'Documents',
+    data: 'Documents Folder',
+    icon: 'pi pi-fw pi-inbox',
+    children: [
+        {
+            key: '0-0',
+            label: 'Work',
+            data: 'Work Folder',
+            icon: 'pi pi-fw pi-cog',
+            children: [
+                { key: '0-0-0', label: 'Expenses.doc', icon: 'pi pi-fw pi-file', data: 'Expenses Document' },
+                { key: '0-0-1', label: 'Resume.doc', icon: 'pi pi-fw pi-file', data: 'Resume Document' }
+            ]
+        },
+        {
+            key: '0-1',
+            label: 'Home',
+            data: 'Home Folder',
+            icon: 'pi pi-fw pi-home',
+            children: [{ key: '0-1-0', label: 'Invoices.txt', icon: 'pi pi-fw pi-file', data: 'Invoices for this month' }]
+        }
+    ]
+},
+...`
+    };
+}

src/app/showcase/doc/treeselect/treeselectdoc.module.ts

@@ -19,10 +19,11 @@ import { StyleDoc } from './styledoc';
 import { VirtualScrollDoc } from './virtualscrolldoc';
 import { FloatLabelModule } from 'primeng/floatlabel';
 import { FilledDoc } from './filleddoc';
+import { LazyDoc } from './lazydoc';
 
 @NgModule({
     imports: [CommonModule, AppCodeModule, AppDocModule, TreeSelectModule, FormsModule, ReactiveFormsModule, RouterModule, FloatLabelModule],
     exports: [AppDocModule],
-    declarations: [ImportDoc, BasicDoc, MultipleDoc, CheckboxDoc, VirtualScrollDoc, FilterDoc, FloatLabelDoc, InvalidDoc, DisabledDoc, StyleDoc, AccessibilityDoc, ReactiveFormsDoc, FilledDoc]
+    declarations: [ImportDoc, BasicDoc, MultipleDoc, CheckboxDoc, LazyDoc, VirtualScrollDoc, FilterDoc, FloatLabelDoc, InvalidDoc, DisabledDoc, StyleDoc, AccessibilityDoc, ReactiveFormsDoc, FilledDoc]
 })
 export class TreeSelectDocModule {}

src/app/showcase/pages/treeselect/treeselectdemo.ts

@@ -12,6 +12,7 @@ import { MultipleDoc } from '@doc/treeselect/multipledoc';
 import { StyleDoc } from '@doc/treeselect/styledoc';
 import { VirtualScrollDoc } from '@doc/treeselect/virtualscrolldoc';
 import { FilledDoc } from '@doc/treeselect/filleddoc';
+import { LazyDoc } from '@doc/treeselect/lazydoc';
 
 @Component({
     templateUrl: './treeselectdemo.html'
@@ -48,6 +49,11 @@ export class TreeSelectDemo {
             label: 'Virtual Scroll',
             component: VirtualScrollDoc
         },
+        {
+            id: 'lazy',
+            label: 'Lazy',
+            component: LazyDoc
+        },
         {
             id: 'filter',
             label: 'Filter',