Paging in Angular Treegrid component

9 Jan 202316 minutes to read

Paging provides an option to display TreeGrid data in page segments. To enable paging, set the allowPaging to true. When paging is enabled, pager component renders at the bottom of the treegrid.
Paging options can be configured through the pageSettings.

To use paging, inject the Page module in the treegrid.

import { Component, OnInit } from '@angular/core';
import { sampleData } from './datasource';

@Component({
    selector: 'app-container',
    template: `<ejs-treegrid [dataSource]='data'  [treeColumnIndex]='1' [allowPaging]='true' [pageSettings]='pageSettings' childMapping='subtasks' >
        <e-columns>
                    <e-column field='taskID' headerText='Task ID' textAlign='Right' width=90></e-column>
                    <e-column field='taskName' headerText='Task Name' textAlign='Left' width=180></e-column>
                    <e-column field='startDate' headerText='Start Date' textAlign='Right' format='yMd' width=90></e-column>
                    <e-column field='duration' headerText='Duration' textAlign='Right' width=80></e-column>
        </e-columns>
                </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: Object[];
    public pageSettings: Object ;

    ngOnInit(): void {
        this.data = sampleData;
        this.pageSettings = {pageSize: 7};
    }
}
import { NgModule,ViewChild } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TreeGridModule } from '@syncfusion/ej2-angular-treegrid';
import { PageService, SortService, FilterService } from '@syncfusion/ej2-angular-treegrid';
import { AppComponent } from './app.component';
import {ButtonModule} from '@syncfusion/ej2-angular-buttons';
import { DropDownListAllModule } from '@syncfusion/ej2-angular-dropdowns';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        TreeGridModule,
        ButtonModule,
        DropDownListAllModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [PageService,
                SortService,
                FilterService]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

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

You can achieve better performance by using treegrid paging to fetch only a pre-defined number of records from the data source.
You can navigate to the target pages programmatically by passing the page number into the goToPage method in the tree grid.

Page Size Mode

Two behaviors are available in TreeGrid paging to display certain number of records in a current page. Following are the two types of pageSizeMode.

  • All : This is the default mode. The number of records in a page is based on pageSize property.
  • Root : The number of root nodes or the 0th level records to be displayed per page is based on pageSize property.

With pageSizeMode property as Root, only the root level or the 0th level records are considered in records count.

import { Component, OnInit } from '@angular/core';
import { sampleData } from './datasource';

@Component({
    selector: 'app-container',
    template: `<ejs-treegrid [dataSource]='data' height='265' [treeColumnIndex]='1' [allowPaging]='true' [pageSettings]='pageSettings' childMapping='subtasks' >
        <e-columns>
                    <e-column field='taskID' headerText='Task ID' textAlign='Right' width=90></e-column>
                    <e-column field='taskName' headerText='Task Name' textAlign='Left' width=180></e-column>
                    <e-column field='startDate' headerText='Start Date' textAlign='Right' format='yMd' width=90></e-column>
                    <e-column field='duration' headerText='Duration' textAlign='Right' width=80></e-column>
        </e-columns>
                </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: Object[];
    public pageSettings: Object ;

    ngOnInit(): void {
        this.data = sampleData;
        this.pageSettings = {pageSize: 2, pageSizeMode: 'Root'};
    }
}
import { NgModule,ViewChild } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TreeGridModule } from '@syncfusion/ej2-angular-treegrid';
import { PageService, SortService, FilterService } from '@syncfusion/ej2-angular-treegrid';
import { AppComponent } from './app.component';
import {ButtonModule} from '@syncfusion/ej2-angular-buttons';
import { DropDownListAllModule } from '@syncfusion/ej2-angular-dropdowns';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        TreeGridModule,
        ButtonModule,
        DropDownListAllModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [PageService,
                SortService,
                FilterService]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

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

Template

You can use custom elements inside the pager instead of default elements.
The custom elements can be defined by using the template property.
Inside this template, you can access the currentPage, pageSize, pageCount, totalPage and totalRecordCount values.

import { Component, OnInit,ViewChild } from '@angular/core';
import { sampleData } from './datasource';
import {TreeGridComponent} from '@syncfusion/ej2-angular-treegrid';
import { ChangeEventArgs } from '@syncfusion/ej2-inputs';

@Component({
    selector: 'app-container',
    template: `<ejs-treegrid #treegrid [dataSource]='data' height=250 [treeColumnIndex]='1' [allowPaging]='true' childMapping='subtasks' >
       <ng-template #pagerTemplate let-data>
    <div class="e-pagertemplate">
        <div class="col-lg-12 control-section">
            <div class="content-wrapper"  style="margin-top:5px;margin-left:30px;border: none; display: inline-block ">
              <ejs-numerictextbox format='###.##' step='1' width='75' min='1' max='3' value=
              (change)='change($event)'></ejs-numerictextbox>
            </div>
        </div>
        <div id="totalPages" class="e-pagertemplatemessage"
         style="margin-top:5px;margin-left:30px;border: none; display: inline-block ">
         <span class="e-pagenomsg"> of  pages
         ( items)</span>
      </div>
    </div>
    </ng-template>
        <e-columns>
                    <e-column field='taskID' headerText='Task ID' textAlign='Right' width=90></e-column>
                    <e-column field='taskName' headerText='Task Name' textAlign='Left' width=180></e-column>
                    <e-column field='startDate' headerText='Start Date' textAlign='Right' format='yMd' width=90></e-column>
                    <e-column field='duration' headerText='Duration' textAlign='Right' width=80></e-column>
        </e-columns>
                </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: Object[];
    @ViewChild('treegrid')
    public treeGridObj: TreeGridComponent;
    ngOnInit(): void {
        this.data = sampleData;
    }
       change(args:ChangeEventArgs){
            this.treeGridObj.goToPage(args.value);
            }
}
import { NgModule,ViewChild } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TreeGridModule } from '@syncfusion/ej2-angular-treegrid';
import { PageService, SortService, FilterService } from '@syncfusion/ej2-angular-treegrid';
import { AppComponent } from './app.component';
import { NumericTextBoxComponent } from '@syncfusion/ej2-angular-inputs';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        TreeGridModule,
    ],
    declarations: [AppComponent,NumericTextBoxComponent],
    bootstrap: [AppComponent],
    providers: [PageService,
                SortService,
                FilterService]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

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

Pager with Page Size Dropdown

The pager Dropdown allows you to change the number of records in the TreeGrid dynamically. It can be enabled by defining the pageSettings.pageSizes property as true.

pageSettings: {pageSize: 7, pageSizes: true},

Page size dropdown

How to render Pager at the Top of the TreeGrid

By default, Pager will be rendered at the bottom of the TreeGrid. You can also render the Pager at the top of the TreeGrid by using the dataBound event.

import { Component, OnInit,ViewChild } from '@angular/core';
import { sampleData } from './datasource';
import {TreeGridComponent} from '@syncfusion/ej2-angular-treegrid';
@Component({
    selector: 'app-container',
    template: `<ejs-treegrid #treegrid [dataSource]='data' (dataBound)='dataBound()' [treeColumnIndex]='1' [allowPaging]='true' [pageSettings]='pageSettings' childMapping='subtasks' >
        <e-columns>
                    <e-column field='taskID' headerText='Task ID' textAlign='Right' width=90></e-column>
                    <e-column field='taskName' headerText='Task Name' textAlign='Left' width=180></e-column>
                    <e-column field='startDate' headerText='Start Date' textAlign='Right' format='yMd' width=90></e-column>
                    <e-column field='duration' headerText='Duration' textAlign='Right' width=80></e-column>
        </e-columns>
                </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: Object[];
    public pageSettings: Object ;
    public initialGridLoad: boolean;
    @ViewChild('treegrid')
    public treeGridObj: TreeGridComponent;
    ngOnInit(): void {
        this.data = sampleData;
        this.pageSettings = {pageSize: 7, pageSizes: true};
        this.initialGridLoad = true;
    }
    dataBound(){
    if (this.initialGridLoad) {
        this.initialGridLoad = false;
        var pager = document.getElementsByClassName('e-gridpager');
        var topElement;
        if ( this.treeGridObj.toolbar) {
            topElement = document.getElementsByClassName('e-toolbar');
        } else {
            topElement = document.getElementsByClassName('e-gridheader');
        }
        topElement[0].before(pager[0]);
    }
}
}
import { NgModule,ViewChild } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TreeGridModule } from '@syncfusion/ej2-angular-treegrid';
import { PageService, SortService, FilterService } from '@syncfusion/ej2-angular-treegrid';
import { AppComponent } from './app.component';
import {ButtonModule} from '@syncfusion/ej2-angular-buttons';
import { DropDownListAllModule } from '@syncfusion/ej2-angular-dropdowns';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        TreeGridModule,
        ButtonModule,
        DropDownListAllModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [PageService,
                SortService,
                FilterService]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

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

During the paging action, the pager component triggers the below three events.

  • The created event triggers when Pager is created.
  • The click event triggers when the numeric items in the pager is clicked.
  • The dropDownChanged event triggers when pageSize DropDownList value is selected.
  • You can get the pager element by getPager method in the tree grid.
    You can refer to our Angular Tree Grid feature tour page for its groundbreaking feature representations. You can also explore our Angular Tree Grid example to knows how to present and manipulate data.