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Tree View

Load Data on Demand

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In those special cases when the built-in Virtual Mode fails, you can gain full control over data loading in the createChildren function.This function is called each time a user expands the TreeView node that has not been expanded before. In the createChildren function, you get data from a server or other sources and then form the collection of child nodes from this data.

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import React from 'react'; import TreeView from 'devextreme-react/tree-view'; import 'whatwg-fetch'; class App extends React.Component { render() { return ( <React.Fragment> <TreeView id={'simple-treeview'} dataStructure={'plain'} rootValue={''} height={500} createChildren={this.createChildren} /> </React.Fragment> ); } createChildren(parent) { let parentId = parent ? parent.itemData.id : ''; return fetch(`https://js.devexpress.com/Demos/Mvc/api/TreeViewData?parentId=${parentId}`) .then(response => response.json()) .catch(() => { throw 'Data Loading Error'; }); } } 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/19.1.6/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/19.1.6/css/dx.light.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> <link rel="stylesheet" type="text/css" href="styles.css" /> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="app"></div> </div> </body> </html>
System.config({ transpiler: 'plugin-babel', paths: { 'npm:': 'https://unpkg.com/' }, defaultExtension: 'js', map: { 'react': 'npm:react@16/umd/react.development.js', 'react-dom': 'npm:react-dom@16/umd/react-dom.development.js', 'prop-types': 'npm:prop-types/prop-types.js', 'devextreme': 'npm:devextreme@19.1', 'devextreme-react': 'npm:devextreme-react@19.1', 'jszip': 'npm:jszip@3.1.3/dist/jszip.min.js', 'quill': 'npm:quill@1.3.6/dist/quill.js', 'devexpress-diagram': 'npm:devexpress-diagram', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.js', // SystemJS plugins 'plugin-babel': 'npm:systemjs-plugin-babel@0/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel@0/systemjs-babel-browser.js' }, packages: { 'devextreme': { defaultExtension: 'js' }, 'devextreme-react': { main: 'index.js' } }, babelOptions: { sourceMaps: false, stage0: true, react: true } });