Angular PrimeNG Table Lazy Loading

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 Table Lazy Loading in Angular PrimeNG.

Angular PrimeNG Table Lazy Loading is used to lazy load the data of the TreeTable component. It loads the data when required and makes the TreeTable more interactive and user-friendly.

Syntax:

// In app.component.html
<p-table
    [columns]="cols"
    [value]="tableData"
    [lazy]="true"
    (onLazyLoad)="loadNodes($event)"
    [loading]="loading">
</p-table>

// In app.component.ts 
loadNodes(event) {
    // lazy function
}

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:

Example 1: Below is a simple example demonstrating the use of the Angular PrimeNG Table Lazy Loading.

app.component.html

<h2 style="color: green">GeeksforGeeks</h2>
<h4>Angular PrimeNG Table Lazy Loading</h4>

<p-table
    [value]="tableData"
    [lazy]="true"
    (onLazyLoad)="loadNodes($event)"
    [loading]="loading">
    <ng-template pTemplate="header">
        <tr>
            <th>First Name</th>
            <th>Last Name</th>
            <th>Age</th>
        </tr>
    </ng-template>

    <ng-template pTemplate="body" let-people>
        <tr>
            <td>{{ people.firstname }}</td>
            <td>{{ people.lastname }}</td>
            <td>{{ people.age }}</td>
        </tr>
    </ng-template>
</p-table>

app.component.ts

import { Component } from '@angular/core';
import { NodeService } from './nodeservice';

interface People {
    firstname?: string;
    lastname?: string;
    age?: string;
}

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
})
export class AppComponent {
    tableData: People[] = [];
    cols: any[] = [];
    loading: boolean = false;
    constructor(private nodeService: NodeService) { }

    ngOnInit() {
        this.cols = [
            { field: 'firstname', header: 'First Name' },
            { field: 'lastname', header: 'Last Name' },
            { field: 'age', header: 'Age' },
        ];
        this.loading = true;
    }
    loadNodes(event: any) {
        this.loading = true;
        setTimeout(() => {
            this.loading = false;
            this.tableData = [
                {
                    firstname: 'David',
                    lastname: 'ace',
                    age: '40',
                },
                {
                    firstname: 'AJne',
                    lastname: 'west',
                    age: '40',
                },
                {
                    firstname: 'Mak',
                    lastname: 'Lame',
                    age: '40',
                },
                {
                    firstname: 'Peter',
                    lastname: 'raw',
                    age: '40',
                },
                {
                    firstname: 'Kane',
                    lastname: 'James',
                    age: '40',
                },
            ];
        }, 1000);
    }
}

app.module.ts

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 { RouterModule } from '@angular/router';

import { AppComponent } from './app.component';
import { NodeService } from './nodeservice';

import { TreeTableModule } from 'primeng/treetable';
import { ButtonModule } from 'primeng/button';
import { DialogModule } from 'primeng/dialog';
import { MultiSelectModule } from 'primeng/multiselect';
import { InputTextModule } from 'primeng/inputtext';
import { ToastModule } from 'primeng/toast';
import { ContextMenuModule } from 'primeng/contextmenu';
import { TableModule } from 'primeng/table';

@NgModule({
    imports: [
        BrowserModule,
        BrowserAnimationsModule,
        TreeTableModule,
        ToastModule,
        TableModule,
        DialogModule,
        ButtonModule,
        MultiSelectModule,
        InputTextModule,
        ContextMenuModule,
        HttpClientModule,
        FormsModule,
        RouterModule.forRoot([{ path: '', component: AppComponent }]),
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [NodeService],
})
export class AppModule { }

Output:

Example 2: Below is another example demonstrating the use of the Angular PrimeNG Table Lazy Loading. In this example, we lazy-loaded the data for 5 seconds.

app.component.html

<h2 style="color: green">GeeksforGeeks</h2>
<h4>Angular PrimeNG Table Lazy Loading</h4>

<p-table
    [value]="tableData"
    [lazy]="true"
    (onLazyLoad)="loadNodes($event)"
    [loading]="loading">
    <ng-template pTemplate="header">
        <tr>
            <th>First Name</th>
            <th>Last Name</th>
            <th>Age</th>
        </tr>
    </ng-template>

    <ng-template pTemplate="body" let-people>
        <tr>
            <td>{{ people.firstname }}</td>
            <td>{{ people.lastname }}</td>
            <td>{{ people.age }}</td>
        </tr>
    </ng-template>
</p-table>

app.component.ts

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

interface People {
    firstname?: string;
    lastname?: string;
    age?: string;
}

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
})
export class AppComponent {
    tableData: People[] = [];
    cols: any[] = [];
    loading: boolean = false;
    constructor(private nodeService: NodeService) { }

    ngOnInit() {
        this.cols = [
            { field: 'firstname', header: 'First Name' },
            { field: 'lastname', header: 'Last Name' },
            { field: 'age', header: 'Age' },
        ];
        this.loading = true;
    }
    loadNodes(event: any) {
        this.loading = true;
        setTimeout(() => {
            this.loading = false;
            this.tableData = [
                {
                    firstname: 'David',
                    lastname: 'ace',
                    age: '40',
                },
                {
                    firstname: 'AJne',
                    lastname: 'west',
                    age: '40',
                },
                {
                    firstname: 'Mak',
                    lastname: 'Lame',
                    age: '40',
                },
                {
                    firstname: 'Peter',
                    lastname: 'raw',
                    age: '40',
                },
                {
                    firstname: 'Kane',
                    lastname: 'James',
                    age: '40',
                },
            ];
        }, 5000);
    }
}

app.module.ts

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 { RouterModule } from '@angular/router';

import { AppComponent } from './app.component';
import { NodeService } from './nodeservice';

import { TreeTableModule } from 'primeng/treetable';
import { ButtonModule } from 'primeng/button';
import { DialogModule } from 'primeng/dialog';
import { MultiSelectModule } from 'primeng/multiselect';
import { InputTextModule } from 'primeng/inputtext';
import { ToastModule } from 'primeng/toast';
import { ContextMenuModule } from 'primeng/contextmenu';
import { TableModule } from 'primeng/table';

@NgModule({
    imports: [
        BrowserModule,
        BrowserAnimationsModule,
        TreeTableModule,
        ToastModule,
        TableModule,
        DialogModule,
        ButtonModule,
        MultiSelectModule,
        InputTextModule,
        ContextMenuModule,
        HttpClientModule,
        FormsModule,
        RouterModule.forRoot([{ path: '', component: AppComponent }]),
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [NodeService],
})
export class AppModule { }

Output:

Reference: https://primefaces.org/primeng/table/lazy