Ways to conceal a table and button in the absence of data for display

I've been working on a way to hide the table and the 'changeState' button when there's no data present. Currently, I have set it up so that a message saying 'No entries in the list!' pops up briefly before disappearing, bringing back the table and button. Is there a better way to achieve this?

Below is the HTML snippet:

<app-header [isHidden]="isHiddenProgressBar"></app-header>
<div class="change">
  <button (click)="changeState()" *ngIf="showButton" color="primary" mat-raised-button>Change state</button>
</div>
<div class="list">
  <app-list *ngIf="visible" [changeObjects]="data"></app-list>
  <ng-container *ngIf="!data">
    No entries in the list!
    </ng-container>
</div>

And here is the corresponding TypeScript code section:

this.data = this.objects;
this.visible = this.objects != null && this.objects.length > 0;
this.showButton = true;

//additional condition for handling empty data
if(!this.objects) {
    this.showButton = false;
    this.visible = false;
}

Your input would be greatly appreciated!

angulartypescript

Answer №1

When considering the lines of code:

this.visible = !this.objects && this.objects.length > 0;

And

if (!this.objects) {

It may fail to account for cases where the array is undefined or empty.

In scenarios where objects is an empty array such as:

this.objects = [];

Or if it is simply undefined:

this.objects = undefined;

The conditions should be adjusted to:

this.visible = (this.objects !== undefined) && (this.objects.length > 0);

And

if (this.objects === undefined || this.objects?.length === 0) {

If you initialize objects with sample data like:

objects: any[] = [
  { id: 1, desc: 'one' },
  { id: 2, desc: 'two' },
  { id: 3, desc: 'three' },
];

Following the suggested conditions will result in a visible button and list for non-empty arrays, while keeping the button and list hidden for empty or undefined data.

To aid in debugging similar conditions in the future, consider incorporating console.log() statements.

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