Angular PrimeNG TreeTable Lazy

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. In this article, we will see how to use TreeTable Lazy Loading in Angular PrimeNG.

Angular PrimeNG TreeTable Lazy 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. It helps to handle the large datasets, i.e., the small amount of data will be loaded by calling the corresponding callbacks every time the paging or sorting is done, instead of loading the entire data.

Syntax:

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

// 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 TreeTable Lazy.

app.component.html

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

<p-treeTable [columns]="cols"
             [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-rowNode let-rowData="rowData">
        <tr>
            <td>
                <p-treeTableToggler [rowNode]="rowNode">
                </p-treeTableToggler>
                {{ rowData.firstname }}
            </td>
            <td>{{ rowData.lastname }}</td>
            <td>{{ rowData.age }}</td>
        </tr>
    </ng-template>
</p-treeTable>

app.component.ts

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 {
  tableData: TreeNode[] = [];
  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.tableData = [
        {
          data: {
            firstname: "David",
            lastname: "ace",
            age: "40",
          },
          children: [
            {
              data: {
                firstname: "Nathan",
                lastname: "ace",

                age: "16",
              },
              children: [
                {
                  data: {
                    firstname: "Abe",
                    lastname: "ace",

                    age: "12",
                  },
                },
                {
                  data: {
                    firstname: "Ksi",
                    lastname: "ace",

                    age: "12",
                  },
                },
              ],
            },
            {
              data: {
                firstname: "Shane",
                lastname: "ace",

                age: "14",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Warner",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                lastname: "ace",
                firstname: "Michelle",
                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Max",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Willy",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Miley",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Sam",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "James",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                lastname: "ace",
                firstname: "Charlie",

                age: "24",
              },
            },
          ],
        },
      ];
      this.loading = false;
    }, 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 { AppComponent } from "./app.component";
import { NodeService } from "./nodeservice";
import { TreeTableModule } from "primeng/treetable";

@NgModule({
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    TreeTableModule,
    HttpClientModule,
    FormsModule,
  ],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
  providers: [NodeService],
})
export class AppModule {}

Output:

Example 2: Below is another example demonstrating the use of the Angular PrimeNG TreeTable Lazy, where we are lazy loading the data for 5 seconds.

app.component.html

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

<p-treeTable [columns]="cols"
             [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-rowNode let-rowData="rowData">
        <tr>
            <td>
                <p-treeTableToggler [rowNode]="rowNode">
                </p-treeTableToggler>
                {{ rowData.firstname }}
            </td>
            <td>{{ rowData.lastname }}</td>
            <td>{{ rowData.age }}</td>
        </tr>
    </ng-template>
</p-treeTable>

app.component.ts

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 {
  tableData: TreeNode[] = [];
  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.tableData = [
        {
          data: {
            firstname: "David",
            lastname: "ace",
            age: "40",
          },
          children: [
            {
              data: {
                firstname: "Nathan",
                lastname: "ace",

                age: "16",
              },
              children: [
                {
                  data: {
                    firstname: "Abe",
                    lastname: "ace",

                    age: "12",
                  },
                },
                {
                  data: {
                    firstname: "Ksi",
                    lastname: "ace",

                    age: "12",
                  },
                },
              ],
            },
            {
              data: {
                firstname: "Shane",
                lastname: "ace",

                age: "14",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Warner",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                lastname: "ace",
                firstname: "Michelle",
                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Max",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Willy",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Miley",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "Sam",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                firstname: "Charlie",
                lastname: "ace",

                age: "24",
              },
            },
          ],
        },
        {
          data: {
            firstname: "James",
            lastname: "ace",

            age: "55",
          },
          children: [
            {
              data: {
                firstname: "Michelle",
                lastname: "ace",

                age: "20",
              },
            },
            {
              data: {
                lastname: "ace",
                firstname: "Charlie",

                age: "24",
              },
            },
          ],
        },
      ];
      this.loading = false;
    }, 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 { AppComponent } from "./app.component";
import { NodeService } from "./nodeservice";
import { TreeTableModule } from "primeng/treetable";

@NgModule({
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    TreeTableModule,
    HttpClientModule,
    FormsModule,
  ],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
  providers: [NodeService],
})
export class AppModule {}

Output:

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