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Tree List

Load Data on Demand

This example demonstrates how to load data on demand every time a user expands a TreeList node. For this purpose, filtering is delegated to the server, and IDs of expanded nodes are sent to the server with every request for data.

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<template> <div> <dx-tree-list id="treelist" :data-source="dataSource" :show-borders="true" key-expr="id" parent-id-expr="parentId" has-items-expr="hasItems" root-value="" > <dx-remote-operations :filtering="true" /> <dx-column data-field="name" /> <dx-column :width="100" :customize-text="customizeText" data-field="size" /> <dx-column :width="150" data-field="createdDate" data-type="date" /> <dx-column :width="150" data-field="modifiedDate" data-type="date" /> </dx-tree-list> </div> </template> <script> import { DxTreeList, DxRemoteOperations, DxColumn } from 'devextreme-vue/tree-list'; import 'whatwg-fetch'; export default { components: { DxTreeList, DxRemoteOperations, DxColumn }, data() { return { dataSource: { load: function(loadOptions) { let parentIdsParam = loadOptions.parentIds; return fetch(`https://js.devexpress.com/Demos/Mvc/api/treeListData?parentIds=${parentIdsParam}`) .then(response => response.json()) .catch(() => { throw 'Data Loading Error'; }); } } }; }, methods: { customizeText(e) { if(e.value !== null) { return `${Math.ceil(e.value / 1024) } KB`; } } } }; </script> <style scoped> #treelist { max-height: 440px; } </style>
import Vue from 'vue'; import App from './App.vue'; new Vue({ el: '#app', components: { App }, template: '<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/19.2.3/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/19.2.3/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"> <span v-if="false">Loading...</span> </div> </div> </body> </html>
System.config({ transpiler: 'plugin-babel', paths: { 'npm:': 'https://unpkg.com/' }, map: { vue: 'npm:vue@2.6.3/dist/vue.esm.browser.js', 'vue-loader': 'npm:dx-systemjs-vue-browser@latest/index.js', 'devextreme': 'npm:devextreme@19.2', 'devextreme-vue': 'npm:devextreme-vue@19.2', jszip: 'npm:jszip@3.1.3/dist/jszip.min.js', 'quill': 'npm:quill@1.3.7/dist/quill.js', 'devexpress-diagram': 'npm:devexpress-diagram', 'devexpress-gantt': 'npm:devexpress-gantt', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.js', 'plugin-babel': 'npm:systemjs-plugin-babel@0/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel@0/systemjs-babel-browser.js' }, meta: { '*.vue': { loader: 'vue-loader' } }, packages: { 'devextreme-vue': { main: 'index.js' }, 'devextreme': { defaultExtension: 'js' } }, babelOptions: { sourceMaps: false, stage0: true } });