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Charts

Load Data On Demand

In this demo, the chart loads data as you pan it. Once a data block is loaded, it stays in memory to reduce requests to the server.

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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.visualRange; 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++; component.showLoadingIndicator(); getDataFrame(ajaxArgs) .then(dataFrame => { this.packetsLock--; dataFrame = dataFrame.map(i => { return { 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(component); }) .catch(() => { this.packetsLock--; 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/21.1.6/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/21.1.6/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@15.7.2/prop-types.js', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.js', 'rrule': 'npm:rrule@2.6.6/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@21.1.6/cjs', 'devextreme-react': 'npm:devextreme-react@21.1.6', 'jszip': 'npm:jszip@3.7.1/dist/jszip.min.js', 'devextreme-quill': 'npm:devextreme-quill@1.4.2/dist/dx-quill.min.js', 'devexpress-diagram': 'npm:devexpress-diagram@2.1.32/dist/dx-diagram.js', 'devexpress-gantt': 'npm:devexpress-gantt@3.0.14/dist/dx-gantt.js', '@devextreme/vdom': 'npm:@devextreme/vdom@1.2.2', 'inferno': 'npm:inferno@7.4.10/dist/inferno.min.js', 'inferno-compat': 'npm:inferno-compat@7.4.10/dist/inferno-compat.min.js', 'inferno-create-element': 'npm:inferno-create-element@7.4.10/dist/inferno-create-element.min.js', 'inferno-dom': 'npm:inferno-dom@1.0.7/dist/inferno-dom.min.js', 'inferno-hydrate': 'npm:inferno-hydrate@7.4.10/dist/inferno-hydrate.min.js', 'inferno-clone-vnode': 'npm:inferno-clone-vnode@7.4.10/dist/inferno-clone-vnode.min.js', 'inferno-create-class': 'npm:inferno-create-class@7.4.10/dist/inferno-create-class.min.js', 'inferno-extras': 'npm:inferno-extras@7.4.10/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' }, packages: { 'devextreme': { defaultExtension: 'js' }, '@devextreme/vdom': { 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", ], babelOptions: { sourceMaps: false, stage0: true, react: true } }; System.config(window.config);