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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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<template> <div> <DxTreeView id="simple-treeview" :create-children="createChildren" :root-value="''" :height="500" data-structure="plain" /> </div> </template> <script> import DxTreeView from 'devextreme-vue/tree-view'; import 'whatwg-fetch'; export default { components: { DxTreeView }, methods: { createChildren: function(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'; }); } } }; </script>
import { createApp } from 'vue'; import App from './App.vue'; createApp(App).mount('#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/20.2.3/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/20.2.3/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> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="app"/> </div> </body> </html>
System.config({ transpiler: 'plugin-babel', meta: { '*.vue': { loader: 'vue-loader' }, }, paths: { 'npm:': 'https://unpkg.com/' }, map: { 'vue': 'npm:vue@3.0.0/dist/vue.esm-browser.js', 'vue-loader': 'npm:dx-systemjs-vue-browser@1.0.15/index.js', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.js', 'mitt': 'npm:mitt/dist/mitt.umd.js', 'rrule': 'npm:rrule@2.6.6/dist/es5/rrule.js', 'luxon': 'npm:luxon@1.25.0/build/global/luxon.min.js', 'es6-object-assign': 'npm:es6-object-assign@1.1.0', 'devextreme': 'npm:devextreme@20.2.3', 'devextreme-vue': 'npm:devextreme-vue@20.2.3', 'jszip': 'npm:jszip@3.5.0/dist/jszip.min.js', 'devextreme-quill': 'npm:devextreme-quill@0.9.5/dist/dx-quill.min.js', 'devexpress-diagram': 'npm:devexpress-diagram@2.0.0/dist/dx-diagram.js', 'devexpress-gantt': 'npm:devexpress-gantt@2.0.0/dist/dx-gantt.js', 'preact': 'npm:preact@10.5.5/dist/preact.js', 'preact/hooks': 'npm:preact@10.5.5/hooks/dist/hooks.js', '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' }, packages: { 'devextreme-vue': { main: 'index.js' }, 'devextreme': { defaultExtension: 'js' }, 'devextreme/events/utils': { main: 'index' }, 'devextreme/events': { main: 'index' }, 'es6-object-assign': { main: './index.js', defaultExtension: 'js' } }, babelOptions: { sourceMaps: false, stage0: true } });