Load Data on Demand
The TreeList can load a remote dataset dynamically as a user expands nodes. The dataset must have a plain structure.
This feature requires client- and server-side configurations. To configure the client-side part, do the following:
-
Send an expanded node's ID to the server
For this, implement the CustomStore's load function. In this demo, we do it in the dataSource configuration object. -
Delegate filtering to the server
Set the remoteOperations.filtering property to true. -
Specify the data field that defines whether the node has children
Use the hasItemsExpr property to set this data field.
Server-side implementation is available in the ASP.NET Core and ASP.NET MVC versions of this demo under the TreeListDataController.cs tab.
NOTE
This demo uses a simple data bind technique that is useful for data display purposes only. When a user clicks a node, TreeList receives a JSON object from the server, which is based on the parentIds property value. This technique does not support the built-in data process operations in TreeList on the server.
If your project needs to process data, do one of the following instead:
- Implement a custom data source. See the Custom Data Source demo.
- Use the DevExtreme.AspNet.Data extension as shown in the Web API Service demo.
Feel free to share demo-related thoughts here.
If you have technical questions, please create a support ticket in the DevExpress Support Center.
If you have technical questions, please create a support ticket in the DevExpress Support Center.
Thank you!
We appreciate your feedback.
We appreciate your feedback.
import React from 'react';
import { TreeList, RemoteOperations, Column } from 'devextreme-react/tree-list';
import 'whatwg-fetch';
const dataSource = {
load(loadOptions) {
const parentIdsParam = loadOptions.parentIds;
const url = new URL('https://js.devexpress.com/Demos/Mvc/api/treeListData');
if (parentIdsParam) {
parentIdsParam.forEach((id) => {
url.searchParams.append('parentIds', id);
});
}
return fetch(url)
.then((response) => response.json())
.catch(() => { throw new Error('Data Loading Error'); });
},
};
class App extends React.Component {
render() {
return (
<TreeList
id="treelist"
dataSource={dataSource}
showBorders={true}
keyExpr="id"
parentIdExpr="parentId"
hasItemsExpr="hasItems"
rootValue=""
>
<RemoteOperations filtering={true} />
<Column dataField="name" />
<Column width={100} customizeText={this.customizeText} dataField="size" />
<Column width={150} dataField="createdDate" dataType="date" />
<Column width={150} dataField="modifiedDate" dataType="date" />
</TreeList>
);
}
customizeText(e) {
if (e.value !== null) {
return `${Math.ceil(e.value / 1024)} KB`;
}
return null;
}
}
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" />
<link rel="stylesheet" type="text/css" href="styles.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>
</head>
<body class="dx-viewport">
<div class="demo-container">
<div id="app"></div>
</div>
</body>
</html>
#treelist {
max-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@15.8.1/prop-types.js',
'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.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@23.1.5/cjs',
'devextreme-react': 'npm:devextreme-react@23.1.5',
'jszip': 'npm:jszip@3.7.1/dist/jszip.min.js',
'devextreme-quill': 'npm:devextreme-quill@1.6.2/dist/dx-quill.min.js',
'devexpress-diagram': 'npm:devexpress-diagram@2.2.1/dist/dx-diagram.js',
'devexpress-gantt': 'npm:devexpress-gantt@4.1.48/dist/dx-gantt.js',
'@devextreme/runtime': 'npm:@devextreme/runtime@3.0.11',
'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',
// 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@2.8.4/standalone.js',
'prettier/parser-html': 'npm:prettier@2.8.4/parser-html.js',
},
packages: {
'devextreme': {
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',
'npm:@devextreme/runtime@3.0.11/inferno/package.json',
],
babelOptions: {
sourceMaps: false,
stage0: true,
react: true,
},
};
System.config(window.config);