Unable to use primeng virtual scroll lazy load

Question

I am trying to implement a lazy load for a large set of data with primeng <p-datatable>. I have done everything documented on the official site, however I could not make it work.

The onLazyLoad callback runs only once at the time of loading the table. It doesn't trigger on each scroll as expected.

<div style="max-height:300px; border:1px solid black;overflow-y:auto">
      <p-dataTable #pocListref [value]="data" rowHover="true" [(selection)] = "selectedData" scrollable="true" scrollHeight="200px" [rows]="4"
      [style]="{'margin-top':'30px'}"  [paginator]="true" [rowsPerPageOptions]="[5,10,20]"
        [lazy]="true" [totalRecords]="totalRecords" (onLazyLoad)="lazyLoad($event)">
        <p-column header="Id">
        <ng-template pTemplate="body" let-index="rowIndex">
            {{index}}
        </ng-template>
        </p-column>
        <p-column  selectionMode="multiple" [style]="{'width':'5%'}"></p-column>
        <p-column field="name" header="Name"[sortable]="true"></p-column>
        <p-column field="age" header="Age" [sortable]="true"></p-column>
        <p-column field="company" header="Company" [sortable]="true"></p-column>
      </p-dataTable>
  </div>

The same works fine with the paginator implementation. I have noticed that it works with paginator only if I do not use virtualScroll attribute, which makes sense, but somehow virtualScroll doesn't make any effect on scrolling.

I know there is already a similar question but it is still answered.

Has someone used the virtual scroll successfully with lazy loading. Any suggestions will be useful.

Answer 1

i use the p-table, but i think it is the same way it does the lazyloading as p-datatable. i fix this problem with a trick. i set the totalRecords as a large number or a number much larger than your current data(e.g. the current data's length is 500, set the totalRecords as 1000), then the lazyloading will be triggered on each scroll

Answer 2

Try like this my example :

here is my updated code without paginator and using virtualScroll

<p-dataTable [value]="resultsArr" scrollable="true" scrollHeight="100px" [rows]="4" virtualScroll="virtualScroll" [style]="{'margin-top':'30px'}" [lazy]="true" [totalRecords]="results.length" (onLazyLoad)="lazyLoad($event)">
<p-column header="Id">
<ng-template pTemplate="body" let-index="rowIndex">
    {{index}}
</ng-template>
</p-column>
<p-column  selectionMode="multiple" [style]="{'width':'5%'}"></p-column>
<p-column field="name" header="Name"[sortable]="true"></p-column>
<p-column field="age" header="Age" [sortable]="true"></p-column>
<p-column field="company" header="Company" [sortable]="true"></p-column>
</p-dataTable>

component.ts

export class Component {
    private results: Array<any> = []; // have 15+ objects in this array
    private resultsArr: Array<any> = [];

constructor() {
    this.results = [{
        name: "david",
        age: 26,
        company: "XYz Company"
    }, {
        name: "david",
        age: 26,
        company: "XYz Company"
    }, {
        name: "david",
        age: 26,
        company: "XYz Company"
    }, {
        name: "david",
        age: 26,
        company: "XYz Company"
    }, {
        name: "david",
        age: 26,
        company: "XYz Company"
    }, {
        name: "david",
        age: 26,
        company: "XYz Company"
    }]
}

    lazyLoad(event: any) {
        setTimeout(() => {
            if (this.results) {
                this.resultsArr = this.results.slice(event.first, (event.first + event.rows));
            }
        }, 250);
    }
}

component.html

<p-dataTable [value]="resultsArr" [lazy]="true" [totalRecords]="results.length" [responsive]="true"
             [paginator]="true" (onLazyLoad)="lazyLoad($event)" [rows]="5" [filterDelay]="500"
             [rowsPerPageOptions]="[5,10,20]" sortField="first_name" [sortOrder]="1">
  <p-column field="id" header="#" [sortable]="true" styleClass="columnId" [filter]="true"></p-column>
  <p-column field="first_name" header="First Name" [sortable]="true"></p-column>
  <p-column field="last_name" header="Last Name" [sortable]="true"></p-column>
</p-dataTable>