What could be causing the error message "why can't shows read property

Within my Ionic-Angular application, I have successfully loaded the content from the database and printed it on the console. However, I am facing an issue where I cannot bind this content to the view. The error message that appears is displayed in https://i.stack.imgur.com/06Sba.png app.html

  <ion-card-content>
  {{homeContent.about}}
  </ion-card-content>

component.ts

constructor(public navCtrl: NavController, navParams: NavParams, public 
   homeService: HomeContentService, 
  public loadingCtrl: LoadingController) {
 this.homeService.geteventHomeContentForPage(this.event.id).subscribe(data=>
 { 
  this.homeContent=data;

  console.log(this.homeContent) 
  console.log(this.homeContent.about) 

 })
}

The output in my console can be seen at https://i.stack.imgur.com/GGkvJ.png

angulartypescriptionic2ionic3

Answer №1

The issue arises from the asynchronous loading of the homeContent property in Angular. As a result, when Angular attempts to display the view, homeContent may not be defined yet, leading to an error when trying to access the about property. One solution is to utilize the elvis operator:

  <ion-card-content>
    {{ homeContent?.about }}
  </ion-card-content>

This informs Angular not to read the about property if homeContent is still null/undefined.

Alternatively, you can prevent this situation by incorporating a check using ngIf, like so:

  <ion-card-content *ngIf="homeContent">
    {{ homeContent.about }}
  </ion-card-content>

In this scenario, the elvis operator (?) is unnecessary since the entire ion-card-content element will not render if the homeContent property is undefined.

An additional approach to sidestep this error is to initialize the homeContent property as an object, ensuring that when attempting to access its about sub-property, it remains null without triggering an Angular error:

public homeContent: any = {};

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