Load Data on Demand

You can use the createChildren function to specify custom logic to load data. This function is called each time a user expands a node that was not expanded before. The node's identifier is passed to the function as an argument. Send this identifier to the data service that should return data for child nodes.

As an alternative, you can enable virtual mode to use the default load logic.

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Backend API

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} expandNodesRecursive={false} createChildren={this.createChildren} /> </React.Fragment> ); } createChildren(parent) { const parentId = parent ? parent.itemData.id : ''; return fetch(`https://js.devexpress.com/Demos/Mvc/api/TreeViewData?parentId=${parentId}`) .then((response) => response.json()) .catch(() => { throw new Error('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/23.1.5/css/dx.light.css" /> <script src="https://unpkg.com/core-js@2.6.12/client/shim.min.js"></script> <script src="https://unpkg.com/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>