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TreeView

Virtual Mode

Documentation

For working with a large amount of data, the TreeView widget provides the Virtual Mode. In this mode, the widget loads a set of child nodes once their parent node is expanded. In this demo, the TreeView is associated with a remote data source. Note that the widget shows a loading indicator, because data loading takes a long time.

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<dx-tree-view [dataSource]="dataSource" dataStructure="plain" keyExpr="Id" displayExpr="Name" parentIdExpr="CategoryId" hasItemsExpr="IsGroup" [virtualModeEnabled]="true" ></dx-tree-view>
import { NgModule, Component, enableProdMode } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'; import { DxTreeViewModule } from 'devextreme-angular'; import DataSource from 'devextreme/data/data_source'; import ODataStore from 'devextreme/data/odata/store'; if(!/localhost/.test(document.location.host)) { enableProdMode(); } @Component({ styleUrls: ['app/app.component.css'], selector: 'demo-app', templateUrl: 'app/app.component.html' }) export class AppComponent { dataSource: any; constructor() { this.dataSource = new DataSource({ store: new ODataStore({ url: 'https://js.devexpress.com/Demos/WidgetsGallery/odata/HierarchicalItems' }) }); } } @NgModule({ imports: [ BrowserModule, DxTreeViewModule ], declarations: [AppComponent], bootstrap: [AppComponent] }) export class AppModule { } platformBrowserDynamic().bootstrapModule(AppModule);
// In real applications, you should not transpile code in the browser. You can see how to create your own application with Angular and DevExtreme here: // https://github.com/DevExpress/devextreme-angular/blob/master/README.md System.config({ transpiler: 'ts', typescriptOptions: { module: "commonjs", emitDecoratorMetadata: true, experimentalDecorators: true }, meta: { 'typescript': { "exports": "ts" } }, paths: { 'npm:': 'https://unpkg.com/' }, map: { 'ts': 'npm:plugin-typescript@7.0.6/lib/plugin.js', 'typescript': 'npm:typescript@2.2.2/lib/typescript.js', '@angular/core': 'npm:@angular/core@4.1.0/bundles/core.umd.js', '@angular/common': 'npm:@angular/common@4.1.0/bundles/common.umd.js', '@angular/compiler': 'npm:@angular/compiler@4.1.0/bundles/compiler.umd.js', '@angular/platform-browser': 'npm:@angular/platform-browser@4.1.0/bundles/platform-browser.umd.js', '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic@4.1.0/bundles/platform-browser-dynamic.umd.js', '@angular/http': 'npm:@angular/http@4.1.0/bundles/http.umd.js', '@angular/router': 'npm:@angular/router@4.1.0/bundles/router.umd.js', '@angular/forms': 'npm:@angular/forms@4.1.0/bundles/forms.umd.js', 'rxjs': 'npm:rxjs@5.3.1', 'devextreme': 'npm:devextreme@17.2', 'jszip': 'npm:jszip@3.1.3/dist/jszip.min.js', 'jquery': 'npm:jquery@3.1.1/dist/jquery.min.js', 'devextreme-angular': 'npm:devextreme-angular@17.2' }, packages: { 'app': { main: './app.component.ts', defaultExtension: 'ts' }, 'devextreme': { defaultExtension: 'js' }, 'devextreme-angular': { main: 'index.js', defaultExtension: 'js' } } });
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/17.2.4/css/dx.spa.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/17.2.4/css/dx.common.css" /> <link rel="dx-theme" data-theme="generic.light" href="https://cdn3.devexpress.com/jslib/17.2.4/css/dx.light.css" /> <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script> <script src="https://unpkg.com/zone.js@0.6.25/dist/zone.js"></script> <script src="https://unpkg.com/reflect-metadata@0.1.3/Reflect.js"></script> <script src="https://unpkg.com/systemjs@0.19.31/dist/system.js"></script> <script src="config.js"></script> <script> System.import('app').catch(console.error.bind(console)); </script> </head> <body class="dx-viewport"> <div class="demo-container"> <demo-app>Loading...</demo-app> </div> </body> </html>