Your search did not match any results.
Charts

Load Data On Demand

In this demo, the range area Chart loads data as you pan it. Once the component loads a data block, this data stays in memory to reduce requests to the server. To implement this functionality, do the following:

  1. Configure a data source.

  2. Configure the Chart to support on-demand data loading.

  3. Implement functions that load the data.

    • In this demo, Chart displays daily information. If a user pan the Chart left or right more than half a day, additional data starts to load. The onVisualRangeChanged initiates this procedure.

    • The uploadDataByVisualRange function analyzes the starting and ending points of the visual range and the bounds of already loaded data. If necessary, it calls the getDataFrame function to obtain new data points. Finally, it reloads the DataSource and saves the current visual range.

    • The getDataFrame Ajax request gets the new data frame from the server.

www.kaggle.com
Backend API
Copy to CodeSandBox
Apply
Reset
import React from 'react'; import DataSource from 'devextreme/data/data_source'; import { Chart, ZoomAndPan, ScrollBar, ArgumentAxis, ValueAxis, Title, Label, Font, Legend, Series, Animation, LoadingIndicator, } from 'devextreme-react/chart'; const wholeRange = { startValue: new Date(2017, 0, 1), endValue: new Date(2017, 11, 31), }; class App extends React.Component { constructor(props) { super(props); this.packetsLock = 0; this.HALFDAY = 43200000; this.chartDataSource = new DataSource({ store: [], sort: 'date', paginate: false, }); this.state = { visualRange: { startValue: new Date(2017, 3, 1), endValue: new Date(2017, 3, 15), }, }; this.handleChange = this.handleChange.bind(this); } render() { return ( <Chart id="chart" title="Temperature in Toronto (2017)" dataSource={this.chartDataSource} onOptionChanged={this.handleChange} > <ZoomAndPan argumentAxis="pan" /> <ScrollBar visible={true} /> <ArgumentAxis argumentType="datetime" visualRangeUpdateMode="keep" visualRange={this.state.visualRange} wholeRange={wholeRange} /> <ValueAxis name="temperature" allowDecimals={false} > <Title text={'Temperature, &deg;C'}> <Font color="#ff950c" /> </Title> <Label> <Font color="#ff950c" /> </Label> </ValueAxis> <Series color="#ff950c" type="rangeArea" argumentField="date" rangeValue1Field="minTemp" rangeValue2Field="maxTemp" name="Temperature range" /> <Animation enabled={false} /> <LoadingIndicator backgroundColor="none"> <Font size={14} /> </LoadingIndicator> <Legend visible={false} /> </Chart> ); } handleChange(e) { if (e.fullName === 'argumentAxis.visualRange') { const stateStart = this.state.visualRange.startValue; const currentStart = e.value.startValue; if (stateStart.valueOf() !== currentStart.valueOf()) { this.setState({ visualRange: e.value }); } this.onVisualRangeChanged(e.component); } } onVisualRangeChanged(component) { const items = component.getDataSource().items(); const { visualRange } = this.state; if (!items.length || items[0].date - visualRange.startValue >= this.HALFDAY || visualRange.endValue - items[items.length - 1].date >= this.HALFDAY) { this.uploadDataByVisualRange(visualRange, component); } } uploadDataByVisualRange(visualRange, component) { const dataSource = component.getDataSource(); const storage = dataSource.items(); const ajaxArgs = { startVisible: getDateString(visualRange.startValue), endVisible: getDateString(visualRange.endValue), startBound: getDateString(storage.length ? storage[0].date : null), endBound: getDateString(storage.length ? storage[storage.length - 1].date : null), }; if (ajaxArgs.startVisible !== ajaxArgs.startBound && ajaxArgs.endVisible !== ajaxArgs.endBound && !this.packetsLock) { this.packetsLock += 1; component.showLoadingIndicator(); getDataFrame(ajaxArgs) .then((dataFrame) => { this.packetsLock -= 1; const componentStorage = dataSource.store(); dataFrame .map((i) => ({ date: new Date(i.Date), minTemp: i.MinTemp, maxTemp: i.MaxTemp, })) .forEach((item) => componentStorage.insert(item)); dataSource.reload(); this.onVisualRangeChanged(component); }) .catch(() => { this.packetsLock -= 1; dataSource.reload(); }); } } } function getDataFrame(args) { let params = '?'; params += `startVisible=${args.startVisible} &endVisible=${args.endVisible} &startBound=${args.startBound} &endBound=${args.endBound}`; return fetch(`https://js.devexpress.com/Demos/WidgetsGallery/data/temperatureData${params}`) .then((response) => response.json()); } function getDateString(dateTime) { return dateTime ? dateTime.toLocaleDateString('en-US') : ''; } export default App;
import React from 'react'; import ReactDOM from 'react-dom'; import App from './App.js'; ReactDOM.render( <App />, document.getElementById('app'), );
<!DOCTYPE html> <html> <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/22.1.5/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/22.1.5/css/dx.light.css" /> <link rel="stylesheet" type="text/css" href="styles.css" /> <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script> <script src="https://unpkg.com/systemjs@0.21.3/dist/system.js"></script> <script type="text/javascript" src="config.js"></script> <script type="text/javascript"> System.import("./index.js"); </script> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="app"></div> </div> </body> </html>
#chart { height: 440px; }
window.config = { transpiler: 'plugin-babel', meta: { 'devextreme/localization.js': { 'esModule': true, }, }, paths: { 'npm:': 'https://unpkg.com/', }, defaultExtension: 'js', map: { 'react': 'npm:react@17.0.2/umd/react.development.js', 'react-dom': 'npm:react-dom@17.0.2/umd/react-dom.development.js', 'prop-types': 'npm:prop-types@15.8.1/prop-types.js', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.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@22.1.5/cjs', 'devextreme-react': 'npm:devextreme-react@22.1.5', 'jszip': 'npm:jszip@3.7.1/dist/jszip.min.js', 'devextreme-quill': 'npm:devextreme-quill@1.5.16/dist/dx-quill.min.js', 'devexpress-diagram': 'npm:devexpress-diagram@2.1.63/dist/dx-diagram.js', 'devexpress-gantt': 'npm:devexpress-gantt@4.1.32/dist/dx-gantt.js', '@devextreme/runtime': 'npm:@devextreme/runtime@3.0.11', 'inferno': 'npm:inferno@7.4.4/dist/inferno.min.js', 'inferno-compat': 'npm:inferno-compat@7.4.11/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@7.4.11/dist/inferno-clone-vnode.min.js', 'inferno-create-class': 'npm:inferno-create-class@7.4.11/dist/inferno-create-class.min.js', 'inferno-extras': 'npm:inferno-extras@7.4.11/dist/inferno-extras.min.js', // SystemJS plugins 'plugin-babel': 'npm:systemjs-plugin-babel@0.0.25/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel@0.0.25/systemjs-babel-browser.js', // Prettier 'prettier/standalone': 'npm:prettier@2.7.1/standalone.js', 'prettier/parser-html': 'npm:prettier@2.7.1/parser-html.js', }, packages: { 'devextreme': { defaultExtension: 'js', }, 'devextreme-react': { main: 'index.js', }, 'devextreme/events/utils': { main: 'index', }, 'devextreme/events': { main: 'index', }, 'es6-object-assign': { main: './index.js', defaultExtension: 'js', }, }, packageConfigPaths: [ 'npm:@devextreme/*/package.json', 'npm:@devextreme/runtime@3.0.11/inferno/package.json', ], babelOptions: { sourceMaps: false, stage0: true, react: true, }, }; System.config(window.config);