Tips for getting Nativescript listview to function properly

I am currently developing an app using nativescript and angular 2. I am facing some issues while trying to implement the nativescript listview component. Whenever I run the app, all I see is " [object object] ".

Below is my view code :


<grid-layout columns="*" rows="*">
   <ListView [items]="itemsd" class="listview" #LISTV>
       <ListView.itemTemplate>
            <grid-layout columns="50, *" rows="*" class="item item-avatar">
                <image src="{{ '~/images/' + img }}" col="0"></image>
                <stack-layout col="1">
                    <label text="{{ artist }}" class="h2" col="1"></label>
                    <label text="{{ title }}" class="p" col="1"></label>
                </stack-layout>
            </grid-layout>
       </ListView.itemTemplate>
   </ListView>
</grid-layout>

This is my typescript code :


ngOnInit(): void {
    this.fakeListItems = [{
        "img":"ANDY.jpg",
        "artist":"ANDY",
        "title":"A User"
    }]
    this.itemsd = new ObservableArray(this.fakeListItems);
}

I have tried multiple ways to resolve the issue with the listview component, however, due to unclear documentation and various versions from different sources, I am unable to find a solution. Can someone please guide me on how to make it work properly?

Thank you.

angulartypescriptnativescript

Answer №1

Perhaps a mix of syntaxes is causing the issue. Have you tried modifying your [items]="itemsd" to items="{{itemsd}}"?

Below is some Angular 2.3 NS code from one of my demo-apps that was functioning correctly:

  <ListView items="{{ peripherals }}" itemTap="{{ onPeripheralTap }}" separatorColor="#ffffff">
      <ListView.itemTemplate>
          <StackLayout orientation="horizontal">
              <StackLayout cssClass="padded-label-stack" width="60%">
                <Label horizontalAlignment="left" text="{{ advertisement }}"/>
                <Label horizontalAlignment="left" text="{{ number1 + ' coins for €' + number2 }}"/>
              </StackLayout>
              <StackLayout cssClass="padded-label-stack" width="40%">
                <Label horizontalAlignment="right" text="{{ 'Time: ' + timestamp }}"/>
                <Label horizontalAlignment="right" text="{{ distance + 'm away' }}"/>
              </StackLayout>
          </StackLayout>
      </ListView.itemTemplate>
  </ListView>

Your ts-code doesn't seem to significantly differ from mine, except that you aren't actively making your object Observable. You are initializing your array correctly.

observablePeripheralArray = new observableArray.ObservableArray();
peripheralArray = new Array();
peripherals = this.observablePeripheralArray;

var that = this;
var onDiscovered = function (result) {
  let extended = new ExtendedPeripheral(result);
  var obsp = new Observable(extended);
  ...
  that.observablePeripheralArray.splice(i, 0, obsp);

One thing to consider: It might be helpful to use Visual Studio Code with NativeScript plugins so you can debug and see exactly what your items are. Alternatively, you could try using JSON.stringify(this.itemsd[0]) to check if your structure is correct. If your objects always have the same fields, creating a class for them could also be beneficial.

Answer №2

It appears that there was a misunderstanding in the syntax used, switching from {{ }} to [ ]

<grid-layout columns="*" rows="*">
     <ListView [items]="itemsd" class="listview" #LISTV>
          <ListView.itemTemplate>
                <grid-layout columns="50, *" rows="*" class="item item-avatar">
                        <image [src]="'~/images/'+img" col="0" ></image>
                              <stack-layout col="1">
                                  <label [text]="artist" class="h2" col="1"></label>
                                  <label [text]="title" class="p" col="1"></label>
                               </stack-layout>
                 </grid-layout>
            </ListView.itemTemplate>
       </ListView>
</grid-layout>

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