Angular PrimeNG Tree Horizontal

Last Updated : 26 Apr, 2025

Angular PrimeNG is an open-source framework with a rich set of native Angular UI components that are used for great styling and this framework is used to make responsive websites with very much ease. This article will show us how to use the Tree Horizontal in Angular PrimeNG.

Tree Horizontal displays Tree Data in Horizontal Order. we can easily modify, manipulate, and show the data in a Horizontal layout using Horizontal. For that, we use the layout property and set it to "horizontal".

Syntax:

<p-tree 
       [value]="..." 
    layout="horizontal">
</p-tree>

Creating Angular application & Module Installation:

Step 1: Create an Angular application using the following command.

ng new appname

Step 2: After creating your project folder i.e. appname, move to it using the following command.

cd appname

Step 3: Install PrimeNG in your given directory.

npm install primeng --save
npm install primeicons --save

Project Structure: It will look like the following:

Steps to run the application: Run the below command to see the output

ng serve --open

Example 1: Below is a simple example demonstrating the use of the Angular PrimeNG Tree Horizontal.

app.component.html

HTML

<h2 style="color: green">GeeksforGeeks</h2>
<h4>Angular PrimeNG Tree Horizontal</h4>
<p-tree [value]="files1" layout="horizontal"></p-tree>

app.component.ts

JavaScript

import { Component, OnInit } from '@angular/core';
import { TreeNode } from 'primeng/api';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
})

export class AppComponent {
    files1: TreeNode[] = [];

    constructor() {}

    ngOnInit() {
        this.files1 = [
            {
              label: 'A',
              children: [
                {
                  label: 'B',

                  children: [
                    {
                      label: 'C',
                    },
                    {
                      label: 'D',
                    },
                  ],
                },
                {
                  label: 'E',

                  children: [
                    {
                      label: 'F',
                    },
                  ],
                },
              ],
            },
            {
              label: 'G',

              children: [
                  {
                    label: 'H',
                  },
                  {
                    label: 'I',
                  },
                  {
                    label: 'J',
                  },
              ],
            },
        ];
    }
}

app.module.ts

JavaScript

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { BrowserAnimationsModule } 
    from '@angular/platform-browser/animations';
import { AppComponent } from './app.component';
import { TreeModule } from 'primeng/tree';
import { ButtonModule } from 'primeng/button';
import { InputTextModule } from 'primeng/inputtext';

@NgModule({
    imports: [
        BrowserModule,
        BrowserAnimationsModule,
        TreeModule,
        ButtonModule,
        InputTextModule,
        HttpClientModule,
        FormsModule,
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [],
})

export class AppModule {}

Output:

Example 2: Below is another example demonstrating the use of the Angular PrimeNG Tree Horizontal. In this example, we are making a Tree Component with icons along with the text.

app.component.html

HTML

<h2 style="color: green">GeeksforGeeks</h2>
<h4>Angular PrimeNG Tree Horizontal</h4>
<p-tree [value]="files1" layout="horizontal"> </p-tree>

app.component.ts

JavaScript

import { Component, OnInit } from '@angular/core';
import { NodeService } from './nodeservice';
import { TreeNode } from 'primeng/api';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
})

export class AppComponent {
    files1: TreeNode[] = [];

    constructor(private nodeService: NodeService) { }

    ngOnInit() {
        this.files1 = [
            {
                label: 'A',
                expandedIcon: 'pi pi-folder-open',
                collapsedIcon: 'pi pi-folder',
                children: [
                    {
                        label: 'B',
                        expandedIcon: 'pi pi-folder-open',
                        collapsedIcon: 'pi pi-folder',
                        children: [
                            {
                                label: 'C',
                                icon: 'pi pi-folder',
                            },
                            {
                                label: 'D',
                                icon: 'pi pi-folder',
                            },
                        ],
                    },
                    {
                        label: 'E',
                        expandedIcon: 'pi pi-folder-open',
                        collapsedIcon: 'pi pi-folder',
                        children: [
                            {
                                label: 'F',
                                icon: 'pi pi-folder',
                            },
                        ],
                    },
                ],
            },
            {
                label: 'G',
                collapsedIcon: 'pi pi-folder',
                expandedIcon: 'pi pi-folder-open',
                children: [
                    {
                        label: 'H',
                        icon: 'pi pi-folder',
                    },
                    {
                        label: 'I',
                        icon: 'pi pi-folder',
                    },
                    {
                        label: 'J',
                        icon: 'pi pi-folder',
                    },
                ],
            },
        ];
    }
}

app.module.ts

JavaScript

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { BrowserAnimationsModule } 
    from '@angular/platform-browser/animations';
import { AppComponent } from './app.component';
import { NodeService } from './nodeservice';
import { TreeModule } from 'primeng/tree';
import { ButtonModule } from 'primeng/button';
import { InputTextModule } from 'primeng/inputtext';

@NgModule({
    imports: [
        BrowserModule,
        BrowserAnimationsModule,
        TreeModule,
        ButtonModule,
        InputTextModule,
        HttpClientModule,
        FormsModule,
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [NodeService],
})

export class AppModule { }