How to check the length of an Observable array

Solution 1:

You can use the | async pipe:

<div *ngIf="(list$ | async)?.length==0">No records found.</div>

Update - 2021-2-17

<ul *ngIf="(list$| async) as list; else loading">
   <li *ngFor="let listItem of list">
      {{ listItem.text }}
   </li>
</ul>

<ng-template #loading>
  <p>Shows when no data, waiting for Api</p>
  <loading-component></loading-component>
</ng-template>

Update - Angular Version 6:

If you are loading up a css Skeleton you can use this. If the array has no items it will display the css template. If there is data then fill out the ngFor.

<ul *ngIf="(list$| async)?.length > 0; else loading">
   <li *ngFor="let listItem of list$| async">
      {{ listItem.text }}
   </li>
</ul>

<ng-template #loading>
  <p>Shows when no data, waiting for Api</p>
  <loading-component></loading-component>
</ng-template>

Solution 2:

A solution for .ts-Files:

     this.list.subscribe(result => {console.log(result.length)});

Solution 3:

For Angular 4+, try this

<div *ngIf="list$ | async;let list">
    Length: {{list.length}}
    <div *ngIf="list.length>0">
        <ul>
            <li *ngFor="let item of list">
                {{item.firstName}}
            </li>
        </ul>
    </div>
</div>

Solution 4:

While this answer is correct

<div *ngIf="(list$ | async)?.length === 0">No records found.</div>

Keep in mind that if you are using http client to call backend (in most cases you do) you will get duplicate calls to your API if you have more that one list$ | async. This is because each | async pipe will create new subscriber to your list$ observable.