React Tree View - 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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TS JS

Backend API

import React from 'react'; import TreeView, { TreeViewTypes } from 'devextreme-react/tree-view'; import 'whatwg-fetch'; const createChildren = (parent: TreeViewTypes.Node) => { 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'); }); }; const App = () => ( <React.Fragment> <TreeView id="simple-treeview" dataStructure="plain" rootValue="" height={500} expandNodesRecursive={false} createChildren={createChildren} /> </React.Fragment> ); export default App;

import React from 'react'; import TreeView from 'devextreme-react/tree-view'; import 'whatwg-fetch'; const 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'); }); }; const App = () => ( <React.Fragment> <TreeView id="simple-treeview" dataStructure="plain" rootValue="" height={500} expandNodesRecursive={false} createChildren={createChildren} /> </React.Fragment> ); export default App;

import React from 'react'; import ReactDOM from 'react-dom'; import App from './App.tsx'; ReactDOM.render( <App />, document.getElementById('app'), );

import React from 'react'; import ReactDOM from 'react-dom'; import App from './App.js'; ReactDOM.render(<App />, document.getElementById('app'));

<!DOCTYPE html> <html lang="en"> <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=5.0" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/24.2.3/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.tsx"); </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>