Ensure that the value of a variable in the Ionic/Angular template has been properly initialized

I am currently facing an issue:

I have an array of blog posts. Some of them have photos, while others do not. I aim to display the first photo if any are set. How can I verify whether the URL value in my array is set?

<ion-header>
  <ion-navbar>
    <ion-title>Blogposts</ion-title>
  </ion-navbar>
</ion-header>
<ion-content padding>
  <ion-list>
    <ion-item *ngFor="let post of posts">
      <ion-card>
        <img [src]="post.photos[0].original_size.url"/>
        <ion-card-content>
          <ion-card-title>
          </ion-card-title>
            {{post.summary}}
        </ion-card-content>
      </ion-card>
    </ion-item>
  </ion-list>
</ion-content>
angulartypescriptionic-framework

Answer №1

To ensure that the posts are defined while waiting for asynchronous results, you can include an *ngIf statement with photos.length along with the safe navigation operator.

<ion-item *ngFor="let post of posts">
  <ion-card *ngIf="post?.photos?.length > 0">
    <img [src]="post?.photos[0]?.original_size.url"/>
    <ion-card-content>
      <ion-card-title>
      </ion-card-title>
        {{post.summary}}
    </ion-card-content>
  </ion-card>
</ion-item>

Answer №2

If you want to display an image conditionally in Angular, you can utilize the *ngIf directive along with the let keyword. Additionally, it's a good practice to use existential operators to avoid potential crashes:

<img *ngIf="post?.photos[0]?.original_size?.url; let url" [src]="url">

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