Virtual Scroll: not working with Ionic2.rc0

[GeeKanJi]

Hello,

I migrated my project to Ionic2.rc0, and i have the following error:

polyfills.js:3 Unhandled Promise rejection: Template parse errors:
Can't bind to 'virtualTrackBy' since it isn't a known property of 'ion-card'.
1. If 'ion-card' is an Angular component and it has 'virtualTrackBy' input, then verify that it is part of this module.
2. If 'ion-card' is a Web Component then add "CUSTOM_ELEMENTS_SCHEMA" to the '@NgModule.schemas' of this component to suppress this message.
 ("                    (click)="ViewArticle($event, article, null)"

                              [ERROR ->][virtualTrackBy]="id"

To isolate the problem, I created a new project and I added the virtual scroll as below:

Template:

<ion-list [virtualScroll]="items">
    <ion-list-header>Follow us on Twitter</ion-list-header>
    <ion-item *virtualItem="let item">
      <ion-icon name="ionic" item-left></ion-icon>
      {{item}}
    </ion-item>
  </ion-list>

Component:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

@Component({
  templateUrl: 'contact.html'
})
export class ContactPage {

  public items: Array<string> = [];

  constructor(public navCtrl: NavController) {
    for(let i = 0; i < 100; i++)
    {
      this.items.push('name' +i);
    }
  }
}

When i go to the contact page, i have the following error:

ORIGINAL EXCEPTION: Cannot read property 'indexOf' of undefined
ORIGINAL STACKTRACE:
TypeError: Cannot read property 'indexOf' of undefined
    at calcHeight (http://localhost:8100/build/main.js:64758:21)
    at calcDimensions (http://localhost:8100/build/main.js:64740:26)
    at readDimensions (http://localhost:8100/build/main.js:64952:17)
    at VirtualScroll.update (http://localhost:8100/build/main.js:64964:9)
    at VirtualScroll.ngAfterContentInit (http://localhost:8100/build/main.js:64919:18)
    at DebugAppView._View_ContactPage0.detectChangesInternal (ContactPage.ngfactory.js:219:65)
    at DebugAppView.AppView.detectChanges (http://localhost:8100/build/main.js:10805:14)
    at DebugAppView.detectChanges (http://localhost:8100/build/main.js:10910:44)
    at DebugAppView.AppView.detectViewChildrenChanges (http://localhost:8100/build/main.js:10831:19)
    at DebugAppView.AppView.detectChangesInternal (http://localhost:8100/build/main.js:10816:14)
ERROR CONTEXT:
DebugContext {_view: _View_ContactPage0, _nodeIndex: 11, _tplRow: 9, _tplCol: 2}
Uncaught Error: Error in ./ContactPage class ContactPage - inline template:9:2 caused by: Cannot read property 'indexOf' of undefined

Cordova CLI: 6.3.0
Gulp version: CLI version 1.2.2
Gulp local:
Ionic Framework Version: 2.0.0-rc.0
Ionic CLI Version: 2.1.0
Ionic App Lib Version: 2.1.0-beta.1
OS:
Node Version: v5.12.0

[jgw96]

Hello, thanks for opening an issue with us! Would you mind posting a repo I can use to reproduce this issue?

[GeeKanJi]

Thanks for your answer.

Git repository here:
https://github.com/jeromeXoo/ionic2.rc0.Virtual-Scroll-Not-Working

[ckaeslin]

I figured out that somehow the approxItemHeight is undefined.
So a workaround is to set it manually (since default is 40px I also used 40px http://ionicframework.com/docs/v2/api/components/virtual-scroll/VirtualScroll/#input-properties):

<ion-list [virtualScroll]="items" approxItemHeight="40px">

  <ion-item *virtualItem="let item">
    {{ item }}
  </ion-item>

</ion-list>

This code is working for me with:
Cordova CLI: 6.3.0
Gulp version: CLI version 3.9.1
Gulp local: Local version 3.9.1
Ionic Framework Version: 2.0.0-rc.0
Ionic CLI Version: 2.1.0
Ionic App Lib Version: 2.1.0-beta.1
ios-deploy version: Not installed
ios-sim version: 5.0.8
OS: Mac OS X El Capitan
Node Version: v5.8.0
Xcode version: Xcode 8.0 Build version 8A218a

[ckaeslin]

I've found the issue in the code and created a PR #8350

[GeeKanJi]

Hello,

Thanks for your feedback.

this one solve the following error:

ORIGINAL EXCEPTION: Cannot read property 'indexOf' of undefined

So i can run the blank project with Virtual Scroll without error.

Anyway, i still have the first error in my project:

polyfills.js:3 Unhandled Promise rejection: Template parse errors:
Can't bind to 'virtualTrackBy' since it isn't a known property of 'ion-card'.

To reproduce in the blank/simple project, i have added "[virtualTrackBy]="id". And I have the following error:

Unhandled Promise rejection: Template parse errors:
Can't bind to 'virtualTrackBy' since it isn't a known property of 'ion-item'.
1. If 'ion-item' is an Angular component and it has 'virtualTrackBy' input, then verify that it is part of this module.
2. If 'ion-item' is a Web Component then add "CUSTOM_ELEMENTS_SCHEMA" to the '@NgModule.schemas' of this component to suppress this message.
 (">
    <ion-list-header>Follow us on Twitter</ion-list-header>
    <ion-item *virtualItem="let item" [ERROR ->][virtualTrackBy]="id">
      <ion-icon name="ionic" item-left></ion-icon>
      {{item}}
"): ContactPage@11:38 

Updated repository:
https://github.com/jeromeXoo/ionic2.rc0.Virtual-Scroll-Not-Working

[ckaeslin]

This is a different problem.

virtualTrackBy needs a function as input and should be set on ion-list

this code should work

<ion-content>
  <ion-list [virtualScroll]="items" approxItemHeight="40px" [virtualTrackBy]="customTrackBy">
    <ion-list-header>Follow us on Twitter</ion-list-header>
    <ion-item *virtualItem="let item" >
      <ion-icon name="ionic" item-left></ion-icon>
      {{item}}
    </ion-item>
  </ion-list>
</ion-content>

export class ContactPage {

  public items: Array<any> = [];

  constructor(public navCtrl: NavController) {
    for(let i = 0; i < 100; i++)
    {
      this.items.push({id: i,
         name:'name' +i});
    }
  }

  customTrackBy(index, item) {
    return item.id;
  }

}

let me know if you need further explanations

[GeeKanJi]

Thank you for your explanation.

I was bad using virtualTrackBy function. This does not create an error in previous versions of Ionic.

I close this issue.
Thanks again for your help.

[dalbir]

Virtual Scroll show few items (only 4 items but list have 2003)

HTML Code

<ion-list [virtualScroll]="Searchpayers"
[virtualTrackBy]="PayID"
[approxItemHeight]="'270px'"
[approxHeaderWidth] ="'0px'"
[approxHeaderHeight] ="'0px'">
<ion-item *virtualItem="let item" (click)="SelectPayers(item)">
{{ item.PayCode }} - {{ item.CorpNm }} - {{ item.ContactNo }}

{{ item.ShopCount }}

Please help

[GeeKanJi]

Hi,

Could you try with this:

<ion-list [virtualScroll]="Searchpayers" [virtualTrackBy]="PayID" approxItemHeight="270px" approxItemWidth="100%" approxHeaderWidth ="0px" approxHeaderHeight ="0px"> <ion-item *virtualItem="let item" (click)="SelectPayers(item)">

There is a mix of single and double quote in your code

[ionitron-bot]

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