Load Data On Demand

import { NgModule, Component, ViewChild, enableProdMode, } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'; import { HttpClient, HttpClientModule } from '@angular/common/http'; import { lastValueFrom } from 'rxjs'; import { DxChartModule, DxChartComponent } from 'devextreme-angular'; import DataSource from 'devextreme/data/data_source'; if (!/localhost/.test(document.location.host)) { enableProdMode(); } @Component({ selector: 'demo-app', templateUrl: 'app/app.component.html', styleUrls: ['app/app.component.css'], }) export class AppComponent { @ViewChild(DxChartComponent, { static: false }) component: DxChartComponent; private _visualRange: any = {}; HALFDAY = 43200000; packetsLock = 0; chartDataSource: any; bounds: any; constructor(private httpClient: HttpClient) { this.chartDataSource = new DataSource({ store: [], sort: 'date', paginate: false, }); this.bounds = { startValue: new Date(2017, 0, 1), endValue: new Date(2017, 11, 31), }; this._visualRange = { startValue: new Date(2017, 3, 1), length: { weeks: 2, }, }; } get currentVisualRange(): any { return this._visualRange; } set currentVisualRange(range: any) { this._visualRange.startValue = range.startValue; this._visualRange.endValue = range.endValue; this.onVisualRangeChanged(); } onVisualRangeChanged() { const items = this.component.instance.getDataSource().items(); if (!items.length || items[0].date - this._visualRange.startValue >= this.HALFDAY || this._visualRange.endValue - items[items.length - 1].date >= this.HALFDAY) { this.uploadDataByVisualRange(); } } uploadDataByVisualRange() { const dataSource = this.component.instance.getDataSource(); const storage = dataSource.items(); const ajaxArgs = { startVisible: this.getDateString(this._visualRange.startValue), endVisible: this.getDateString(this._visualRange.endValue), startBound: this.getDateString(storage.length ? storage[0].date : null), endBound: this.getDateString(storage.length ? storage[storage.length - 1].date : null), }; if (ajaxArgs.startVisible !== ajaxArgs.startBound && ajaxArgs.endVisible !== ajaxArgs.endBound && !this.packetsLock) { this.packetsLock++; this.component.instance.showLoadingIndicator(); this.getDataFrame(ajaxArgs) .then((dataFrame: any) => { this.packetsLock--; dataFrame = dataFrame.map((i) => ({ date: new Date(i.Date), minTemp: i.MinTemp, maxTemp: i.MaxTemp, })); const componentStorage = dataSource.store(); dataFrame.forEach((item) => componentStorage.insert(item)); dataSource.reload(); this.onVisualRangeChanged(); }) .catch((error) => { this.packetsLock--; dataSource.reload(); }); } } getDataFrame(args: any) { let params = '?'; params += `startVisible=${args.startVisible}`; params += `&endVisible=${args.endVisible}`; params += `&startBound=${args.startBound}`; params += `&endBound=${args.endBound}`; return lastValueFrom( this.httpClient.get(`https://js.devexpress.com/Demos/WidgetsGallery/data/temperatureData${params}`), ); } getDateString(dateTime: Date) { return dateTime ? dateTime.toLocaleDateString('en-US') : ''; } } @NgModule({ imports: [ BrowserModule, DxChartModule, HttpClientModule, ], declarations: [AppComponent], bootstrap: [AppComponent], }) export class AppModule { } platformBrowserDynamic().bootstrapModule(AppModule);

::ng-deep #chart { height: 440px; }

// 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://js.devexpress.com/Documentation/Guide/Angular_Components/Getting_Started/Create_a_DevExtreme_Application/ window.config = { transpiler: 'ts', typescriptOptions: { module: 'system', emitDecoratorMetadata: true, experimentalDecorators: true, }, meta: { 'typescript': { 'exports': 'ts', }, 'devextreme/localization.js': { 'esModule': true, }, }, paths: { 'npm:': 'https://unpkg.com/', }, map: { 'ts': 'npm:plugin-typescript@4.2.4/lib/plugin.js', 'typescript': 'npm:typescript@4.2.4/lib/typescript.js', '@angular/core': 'npm:@angular/core@12.2.17', '@angular/platform-browser': 'npm:@angular/platform-browser@12.2.17', '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic@12.2.17', '@angular/forms': 'npm:@angular/forms@12.2.17', '@angular/common': 'npm:@angular/common@12.2.17', '@angular/compiler': 'npm:@angular/compiler@12.2.17', 'tslib': 'npm:tslib@2.3.1/tslib.js', 'rxjs': 'npm:rxjs@7.5.3/dist/bundles/rxjs.umd.js', 'rxjs/operators': 'npm:rxjs@7.5.3/dist/cjs/operators/index.js', 'rrule': 'npm:rrule@2.6.4/dist/es5/rrule.js', 'luxon': 'npm:luxon@1.28.0/build/global/luxon.min.js', 'es6-object-assign': 'npm:es6-object-assign@1.1.0', 'devextreme': 'npm:devextreme@22.2.5/cjs', 'devextreme/bundles/dx.all': 'npm:devextreme@22.2.5/bundles/dx.all.js', 'jszip': 'npm:jszip@3.7.1/dist/jszip.min.js', 'devextreme-quill': 'npm:devextreme-quill@1.5.20/dist/dx-quill.min.js', 'devexpress-diagram': 'npm:devexpress-diagram@2.1.72', 'devexpress-gantt': 'npm:devexpress-gantt@4.1.42', 'devextreme-angular': 'npm:devextreme-angular@22.2.5', '@devextreme/runtime': 'npm:@devextreme/runtime@3.0.11', 'inferno': 'npm:inferno@7.4.11/dist/inferno.min.js', 'inferno-compat': 'npm:inferno-compat/dist/inferno-compat.min.js', 'inferno-create-element': 'npm:inferno-create-element@7.4.11/dist/inferno-create-element.min.js', 'inferno-dom': 'npm:inferno-dom/dist/inferno-dom.min.js', 'inferno-hydrate': 'npm:inferno-hydrate@7.4.11/dist/inferno-hydrate.min.js', 'inferno-clone-vnode': 'npm:inferno-clone-vnode/dist/inferno-clone-vnode.min.js', 'inferno-create-class': 'npm:inferno-create-class/dist/inferno-create-class.min.js', 'inferno-extras': 'npm:inferno-extras/dist/inferno-extras.min.js', // Prettier 'prettier/standalone': 'npm:prettier@2.8.4/standalone.js', 'prettier/parser-html': 'npm:prettier@2.8.4/parser-html.js', }, packages: { 'app': { main: './app.component.ts', defaultExtension: 'ts', }, 'devextreme': { defaultExtension: 'js', }, 'devextreme/events/utils': { main: 'index', }, 'devextreme/events': { main: 'index', }, 'es6-object-assign': { main: './index.js', defaultExtension: 'js', }, 'rxjs': { defaultExtension: 'js', }, 'rxjs/operators': { defaultExtension: 'js', }, }, packageConfigPaths: [ 'npm:@devextreme/*/package.json', 'npm:@devextreme/runtime@3.0.11/inferno/package.json', 'npm:@angular/*/package.json', 'npm:@angular/common@12.2.17/*/package.json', 'npm:rxjs@7.5.3/package.json', 'npm:rxjs@7.5.3/operators/package.json', 'npm:devextreme-angular@22.2.5/*/package.json', 'npm:devextreme-angular@22.2.5/ui/*/package.json', 'npm:devextreme-angular@22.2.5/package.json', 'npm:devexpress-diagram@2.1.72/package.json', 'npm:devexpress-gantt@4.1.42/package.json', ], }; System.config(window.config);

<!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/22.2.5/css/dx.light.css" /> <script src="https://unpkg.com/core-js@2.6.12/client/shim.min.js"></script> <script src="https://unpkg.com/zone.js@0.12.0/dist/zone.js"></script> <script src="https://unpkg.com/reflect-metadata@0.1.13/Reflect.js"></script> <script src="https://unpkg.com/systemjs@0.21.3/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>