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Getting started with Angular Dropdown Tree component

06 Oct 2022 / 5 minutes to read

This section explains you about how to create a simple Dropdown Tree component and configure its available functionalities in Angular.

Dependencies

The following list of dependencies are required to use the Dropdown Tree component in your application.

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|-- @syncfusion/ej2-angular-dropdowns
    |-- @syncfusion/ej2-base
    |-- @syncfusion/ej2-data
    |-- @syncfusion/ej2-ng-base
    |-- @syncfusion/ej2-dropdowns
        |-- @syncfusion/ej2-lists
        |-- @syncfusion/ej2-inputs
        |-- @syncfusion/ej2-navigations
        |-- @syncfusion/ej2-popups
            |-- @syncfusion/ej2-buttons

Setup angular environment

Angular provides the easiest way to set angular CLI projects using Angular CLI tool.

Install the CLI application globally to your machine.

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npm install -g @angular/cli

Create an Angular Application

Start a new Angular application using below Angular CLI command.

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ng new my-app
cd my-app

Installing Syncfusion DropDownTree package

Syncfusion packages are distributed in npm as @syncfusion scoped packages. You can get all the Angular Syncfusion package from npm link.

Currently, Syncfusion provides two types of package structures for Angular components,

  1. Ivy library distribution package format
  2. Angular compatibility compiler(Angular’s legacy compilation and rendering pipeline) package.

Ivy library distribution package

Syncfusion Angular packages(>=20.2.36) has been moved to the Ivy distribution to support the Angular Ivy rendering engine and the package are compatible with Angular version 12 and above. To download the package use the below command.

Add @syncfusion/ej2-angular-dropdowns package to the application.

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

Angular compatibility compiled package(ngcc)

For Angular version below 12, you can use the legacy (ngcc) package of the Syncfusion Angular components. To download the ngcc package use the below.

Add @syncfusion/ej2-angular-dropdowns@ngcc package to the application.

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npm install @syncfusion/ej2-angular-dropdowns@ngcc --save

To mention the ngcc package in the package.json file, add the suffix -ngcc with the package version as below.

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@syncfusion/ej2-angular-dropdowns:"20.2.38-ngcc"

Note: If the ngcc tag is not specified while installing the package, the Ivy Library Package will be installed and this package will throw a warning.

Registering Dropdown Tree Module

Import Dropdown Tree module into Angular application(app.module.ts) from the package @syncfusion/ej2-angular-dropdowns.

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import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
// import the DropDownTreeModule for the DropDownTree component
import { DropDownTreeModule } from '@syncfusion/ej2-angular-dropdowns';
import { AppComponent }  from './app.component';

@NgModule({
  //declaration of ej2-angular-dropdowns module into NgModule
  imports:      [ BrowserModule, DropDownTreeModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

Adding CSS Reference

Add Dropdown Tree component’s styles as given below in styles.css.

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@import '../node_modules/@syncfusion/ej2-base/styles/material.css';
@import '../node_modules/@syncfusion/ej2-buttons/styles/material.css';
@import '../node_modules/@syncfusion/ej2-dropdowns/styles/material.css';
@import '../node_modules/@syncfusion/ej2-navigations/styles/material.css';
@import '../node_modules/@syncfusion/ej2-inputs/styles/material.css';
@import '../node_modules/@syncfusion/ej2-popups/styles/material.css';
@import '../node_modules/@syncfusion/ej2-lists/styles/material.css';
@import '../node_modules/@syncfusion/ej2-angular-dropdowns/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 Dropdown Tree component

Modify the template in [src/app/app.component.ts] file to render the Dropdown Tree component. Add the Angular Dropdown Tree by using ejs-dropdowntree selector in template section of the app.component.ts file.

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

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

Binding data source

The Dropdown Tree component can load the 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 Dropdown Tree component.

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

@Component({
selector: 'app-root',
// specifies the template string for the DropDownTree component
template: `<ejs-dropdowntree id='dropdowntree' [fields]='fields' placeholder='Select a Item'></ejs-dropdowntree>`
})
export class AppComponent {
constructor() {
}
// defined the array of data
public data: { [key: string]: Object }[] = [
 {
    nodeId: '01', nodeText: 'Music',
    nodeChild: [
        { nodeId: '01-01', nodeText: 'Gouttes.mp3' }
    ]
 },
 {
    nodeId: '02', nodeText: 'Videos', expanded: true,
    nodeChild: [
        { nodeId: '02-01', nodeText: 'Naturals.mp4' },
        { nodeId: '02-02', nodeText: 'Wild.mpeg' },
    ]
 },
 {
    nodeId: '03', nodeText: 'Documents',
    nodeChild: [
        { nodeId: '03-01', nodeText: 'Environment Pollution.docx' },
        { nodeId: '03-02', nodeText: 'Global Water, Sanitation, & Hygiene.docx' },
        { nodeId: '03-03', nodeText: 'Global Warming.ppt' },
        { nodeId: '03-04', nodeText: 'Social Network.pdf' },
        { nodeId: '03-05', nodeText: 'Youth Empowerment.pdf' },
    ]
 },
];
 //binding data source through fields property
public fields: Object = { dataSource: this.data, value: 'nodeId', text: 'nodeText', child: 'nodeChild' };
}

Run the application

After completing the configuration required to render a basic Dropdown Tree, run the following command to display the output in your default browser.

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ng serve --open

The following example illustrates the output in your browser.

Source
Preview
app.component.ts
app.module.ts
main.ts
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import { Component } from '@angular/core';

@Component({
selector: 'app-container',
// specifies the template string for the DropDownTree component
template: `<ejs-dropdowntree id='dropdowntree' [fields]='fields' placeholder='Select a Item'></ejs-dropdowntree>`
})
export class AppComponent {
constructor() {
}
// defined the array of data
public data: { [key: string]: Object }[] = [
 {
    nodeId: '01', nodeText: 'Music',
    nodeChild: [
        { nodeId: '01-01', nodeText: 'Gouttes.mp3' }
    ]
 },
 {
    nodeId: '02', nodeText: 'Videos', expanded: true,
    nodeChild: [
        { nodeId: '02-01', nodeText: 'Naturals.mp4' },
        { nodeId: '02-02', nodeText: 'Wild.mpeg' },
    ]
 },
 {
    nodeId: '03', nodeText: 'Documents',
    nodeChild: [
        { nodeId: '03-01', nodeText: 'Environment Pollution.docx' },
        { nodeId: '03-02', nodeText: 'Global Water, Sanitation, & Hygiene.docx' },
        { nodeId: '03-03', nodeText: 'Global Warming.ppt' },
        { nodeId: '03-04', nodeText: 'Social Network.pdf' },
        { nodeId: '03-05', nodeText: 'Youth Empowerment.pdf' },
    ]
 },
];
 //binding data source through fields property
public fields: Object = { dataSource: this.data, value: 'nodeId', text: 'nodeText', child: 'nodeChild' };
}
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import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { DropDownTreeModule } from '@syncfusion/ej2-angular-dropdowns';
import { ButtonModule } from '@syncfusion/ej2-angular-buttons';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,FormsModule, ReactiveFormsModule, ButtonModule, DropDownTreeModule
    ],
    declarations: [AppComponent ],
    bootstrap: [AppComponent]
})
export class AppModule { }
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import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

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