Getting started with Angular TreeView component

03 Mar 2021 / 4 minutes to read

This section explains the steps required to create a simple TreeView component, and configure its available functionalities

Setup Angular Environment

You can use Angular CLI to setup your Angular applications. To install Angular CLI use the following command.

npm install -g @angular/cli

Create an Angular Application

Start a new Angular application using below Angular CLI command.

ng new my-app
cd my-app

Adding Syncfusion Treeview package

All the available Essential JS 2 packages are published in npmjs.com registry.

To install Treeview component, use the following command.

npm install @syncfusion/ej2-angular-navigations --save

The —save will instruct NPM to include the Treeview package inside of the dependencies section of the package.json.

Registering Treeview Module

Import Treeview module into Angular application(app.module.ts) from the package @syncfusion/ej2-angular-navigations [src/app/app.module.ts].

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
// import Treeview component Module
import { TreeViewModule } from '@syncfusion/ej2-angular-navigations';
import { AppComponent }  from './app.component';

@NgModule({
  //declaration of Treeview module into NgModule
  imports:      [ BrowserModule, TreeViewModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

Adding CSS Reference

Add Treeview component’s styles as given below in styles.css.

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

Note: If you want to refer the combined component styles, please make use of our CRG (Custom Resource Generator) in your application.

Add Treeview component

Modify the template in [src/app/app.component.ts] file to render the Treeview component. Add the Angular Treeview by using <ejs-treeview> selector in template section of the app.component.ts file.

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  template: `<ejs-treeview id='treeelement' ></ejs-treeview>`
})
export class AppComponent {}

Binding data source

TreeView can load data either from local data sources or remote data services. This can be done using the dataSource property that is a member of the fields property. The dataSource property supports array of JavaScript objects and DataManager. Here, an array of JSON values is passed to the TreeView component.

import { Component, ViewEncapsulation } from '@angular/core';

@Component({
selector: 'app-root',
template: `<ejs-treeview id='treeelement' [fields]='field'></ejs-treeview>`,
encapsulation: ViewEncapsulation.None
})
export class AppComponent {
constructor() {
}
// defined the array of data
 public hierarchicalData: Object[] = [
    { id: '01', name: 'Music', expanded: true,
        subChild: [
            {id: '01-01', name: 'Gouttes.mp3'},
                  ]
    },
    {
        id: '02', name: 'Videos',
        subChild: [
            {id: '02-01', name: 'Naturals.mp4'},
            {id: '02-02', name: 'Wild.mpeg'}
    ]
    },
    {
        id: '03', name: 'Documents',
        subChild: [
            {id: '03-01', name: 'Environment Pollution.docx'},
            {id: '03-02', name: 'Global Water, Sanitation, & Hygiene.docx'},
            {id: '03-03', name: 'Global Warming.ppt'},
            {id: '03-02', name: 'Social Network.pdf'},
            {id: '03-03', name: 'Youth Empowerment.pdf'},
        ]
    }
];
public field:Object ={ dataSource: this.hierarchicalData, id: 'id', text: 'name', child: 'subChild' };
}

Run the application

Use the following command to run the application in browser.

ng serve --open

The output will appear as follows.

Source

Preview

app.component.ts

app.module.ts

main.ts

import { Component } from '@angular/core';

@Component({
selector: 'app-container',
template: `<div id='treeparent'><ejs-treeview id='treeelement' [fields]='field'></ejs-treeview></div>`
})
export class AppComponent {
constructor() {
}
// defined the array of data
public hierarchicalData: Object[] = [
   { id: '01', name: 'Music', expanded: true,
        subChild: [
            {id: '01-01', name: 'Gouttes.mp3'},
                  ]
    },
    {
        id: '02', name: 'Videos',
        subChild: [
            {id: '02-01', name: 'Naturals.mp4'},
            {id: '02-02', name: 'Wild.mpeg'}
    ]
    },
    {
        id: '03', name: 'Documents',
        subChild: [
            {id: '03-01', name: 'Environment Pollution.docx'},
            {id: '03-02', name: 'Global Water, Sanitation, & Hygiene.docx'},
            {id: '03-03', name: 'Global Warming.ppt'},
            {id: '03-02', name: 'Social Network.pdf'},
            {id: '03-03', name: 'Youth Empowerment.pdf'},
        ]
    }
];
public field:Object ={ dataSource: this.hierarchicalData, id: 'id', text: 'name', child: 'subChild' };
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { TreeViewModule } from '@syncfusion/ej2-angular-navigations';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,FormsModule,TreeViewModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);