Accordion tree in Angular Treeview component

3 Dec 20249 minutes to read

Accordion is an interface where a list of items can be collapsed or expanded, but only one list can be collapsed or expanded at a time. You can customize the TreeView to make it behave as an accordion. Refer to the following code sample to create an accordion tree.

app.component.ts

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { TreeViewModule } from '@syncfusion/ej2-angular-navigations'
import { Component, Inject, ViewChild } from '@angular/core';
import { NodeSelectEventArgs } from '@syncfusion/ej2-navigations';
import { TreeViewComponent } from '@syncfusion/ej2-angular-navigations';
/**
 * TreeView Accordion sample
 */
@Component({
imports: [
        FormsModule, TreeViewModule
    ],


standalone: true,
    selector: 'app-container',
    template: `<div id='treeparent'><ejs-treeview id='treeElement' #treevalidate [fields]='field'  (nodeSelected)='nodeSelect($event)' [cssClass]='cssClass'></ejs-treeview></div>`
})
export class AppComponent {

   // Data source for TreeView component
   public continents: Object[] = [
       {
        code: "AF", name: "Africa", countries: [
            { code: "NGA", name: "Nigeria" },
            { code: "EGY", name: "Egypt" },
            { code: "ZAF", name: "South Africa" }
        ]
    },
    {
        code: "AS", name: "Asia", countries: [
            { code: "CHN", name: "China" },
            { code: "IND", name: "India", selected: true },
            { code: "JPN", name: "Japan" }
        ]
    },
    {
        code: "EU", name: "Europe", countries: [
            { code: "DNK", name: "Denmark" },
            { code: "FIN", name: "Finland" },
            { code: "AUT", name: "Austria",
             }
        ]
    },
    {
        code: "NA", name: "North America", countries: [
            { code: "USA", name: "United States of America" },
            { code: "CUB", name: "Cuba" },
            { code: "MEX", name: "Mexico" }
        ]
    },
    {
        code: "OC", name: "Oceania", countries: [
            { code: "AUS", name: "Australia" },
            { code: "NZL", name: "New Zealand" },
            { code: "WSM", name: "Samoa" }
        ]
    }
    ];
    public field:Object ={ dataSource: this.continents,  id: "code", text: "name", child: "countries" };
    public cssClass="accordiontree";

    @ViewChild ('treevalidate') tree?: TreeViewComponent;

    public nodeSelect(args: NodeSelectEventArgs): void {
      if (args.node.classList.contains('e-level-1')) {
        this.tree?.collapseAll();
        this.tree?.expandAll([args.node]);
        (this.tree as TreeViewComponent).expandOn = 'None';
      }
    }
}

styles.css

@import 'node_modules/@syncfusion/ej2-base/styles/material.css';
@import 'node_modules/@syncfusion/ej2-inputs/styles/material.css';
@import 'node_modules/@syncfusion/ej2-buttons/styles/material.css';
@import 'node_modules/@syncfusion/ej2-angular-base/styles/material.css';
@import 'node_modules/@syncfusion/ej2-angular-navigations/styles/material.css';

#treeparent {
    display: block;
    max-width: 350px;
    max-height: 350px;
    margin: auto;
    overflow: auto;
}
.accordiontree .e-list-item.e-level-1 > .e-fullrow, .accordiontree .e-list-item.e-level-1.e-active > .e-fullrow,  .accordiontree .e-list-item.e-level-1.e-hover > .e-fullrow , .accordiontree .e-list-item.e-level-1 > .e-fullrow, .accordiontree .e-list-item.e-level-1.e-active.e-hover > .e-fullrow {
    background-color: darkslateblue;
    border-color: darkslateblue;
}

.accordiontree .e-list-item.e-level-1 > .e-text-content .e-list-text, .accordiontree .e-list-item.e-level-1.e-active > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-1.e-hover > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-1.e-active.e-hover > .e-text-content .e-list-text {
    color: white;
    font-size: 16px;
} 
.accordiontree .e-list-item.e-level- .e-icons.e-icon-collapsible, .accordiontree .e-list-item.e-level-1 .e-icons.e-icon-collapsible,.accordiontree .e-list-item.e-level-1 .e-icon-expandable {
    display: none
}

.accordiontree .e-list-item.e-level-2 > .e-fullrow, .accordiontree .e-list-item.e-level-2.e-active > .e-fullrow,  .accordiontree .e-list-item.e-level-2.e-hover > .e-fullrow , .accordiontree .e-list-item.e-level-2 > .e-fullrow, .accordiontree .e-list-item.e-level-2.e-active.e-hover > .e-fullrow {
    background-color: white;
    border-color: white;
}

.accordiontree .e-list-item.e-level-2 > .e-text-content .e-list-text, .accordiontree .e-list-item.e-level-2.e-active > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-2.e-hover > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-2.e-active.e-hover > .e-text-content .e-list-text {
    color: blue;
    font-size: 14px;
}

main.ts

import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));