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Backend API
import React from 'react';
import TreeView from 'devextreme-react/tree-view';
import DataSource from 'devextreme/data/data_source';
import ODataStore from 'devextreme/data/odata/store';
const dataSource = new DataSource({
store: new ODataStore({
version: 2,
url: 'https://js.devexpress.com/Demos/WidgetsGallery/odata/HierarchicalItems',
}),
});
const App = () => (
<React.Fragment>
<TreeView
dataSource={dataSource}
dataStructure="plain"
keyExpr="Id"
displayExpr="Name"
parentIdExpr="CategoryId"
hasItemsExpr="IsGroup"
virtualModeEnabled={true}
/>
</React.Fragment>
);
export default App;
import React from 'react';
import TreeView from 'devextreme-react/tree-view';
import DataSource from 'devextreme/data/data_source';
import ODataStore from 'devextreme/data/odata/store';
const dataSource = new DataSource({
store: new ODataStore({
version: 2,
url: 'https://js.devexpress.com/Demos/WidgetsGallery/odata/HierarchicalItems',
}),
});
const App = () => (
<React.Fragment>
<TreeView
dataSource={dataSource}
dataStructure="plain"
keyExpr="Id"
displayExpr="Name"
parentIdExpr="CategoryId"
hasItemsExpr="IsGroup"
virtualModeEnabled={true}
/>
</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'),
);
window.exports = window.exports || {};
window.config = {
transpiler: 'ts',
typescriptOptions: {
module: 'system',
emitDecoratorMetadata: true,
experimentalDecorators: true,
jsx: 'react',
},
meta: {
'react': {
'esModule': true,
},
'typescript': {
'exports': 'ts',
},
'devextreme/time_zone_utils.js': {
'esModule': true,
},
'devextreme/localization.js': {
'esModule': true,
},
'devextreme/viz/palette.js': {
'esModule': true,
},
},
paths: {
'npm:': 'https://unpkg.com/',
},
defaultExtension: 'js',
map: {
'ts': 'npm:plugin-typescript@4.2.4/lib/plugin.js',
'typescript': 'npm:typescript@4.2.4/lib/typescript.js',
'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',
'rrule': 'npm:rrule@2.6.4/dist/es5/rrule.js',
'luxon': 'npm:luxon@1.28.1/build/global/luxon.min.js',
'es6-object-assign': 'npm:es6-object-assign@1.1.0',
'devextreme': 'npm:devextreme@24.1.6/cjs',
'devextreme-react': 'npm:devextreme-react@24.1.6/cjs',
'jszip': 'npm:jszip@3.10.1/dist/jszip.min.js',
'devextreme-quill': 'npm:devextreme-quill@1.7.1/dist/dx-quill.min.js',
'devexpress-diagram': 'npm:devexpress-diagram@2.2.11/dist/dx-diagram.js',
'devexpress-gantt': 'npm:devexpress-gantt@4.1.56/dist/dx-gantt.js',
'@devextreme/runtime': 'npm:@devextreme/runtime@3.0.13',
'inferno': 'npm:inferno@7.4.11/dist/inferno.min.js',
'inferno-compat': 'npm:inferno-compat/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/dist/inferno-clone-vnode.min.js',
'inferno-create-class': 'npm:inferno-create-class/dist/inferno-create-class.min.js',
'inferno-extras': 'npm:inferno-extras/dist/inferno-extras.min.js',
'devextreme-cldr-data': 'npm:devextreme-cldr-data@1.0.3',
// 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@2.8.8/standalone.js',
'prettier/parser-html': 'npm:prettier@2.8.8/parser-html.js',
},
packages: {
'devextreme': {
defaultExtension: 'js',
},
'devextreme-react': {
main: 'index.js',
},
'devextreme/events/utils': {
main: 'index',
},
'devextreme/localization/messages': {
format: 'json',
defaultExtension: 'json',
},
'devextreme/events': {
main: 'index',
},
'es6-object-assign': {
main: './index.js',
defaultExtension: 'js',
},
},
packageConfigPaths: [
'npm:@devextreme/*/package.json',
'npm:@devextreme/runtime@3.0.13/inferno/package.json',
],
babelOptions: {
sourceMaps: false,
stage0: true,
react: true,
},
};
System.config(window.config);
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/24.1.6/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>
When the data source is remote, the TreeView requests data for each expanded node. To prevent this for nodes that do not nest others, set the hasItems field to false for the corresponding data objects.
This demo enables virtual mode with a remote data source and uses the hasItemsExpr property to specify a custom name for the hasItems field.
As an alternative to virtual mode, you can use a custom logic to process requested data. To do this, specify the createChildren function as shown in the Load Data on Demand demo.