Tips for managing variables to display or hide in various components using Angular

In this example, there are 3 main components:

The first component is A.component.ts: This is the parent component where an HTTP call is made to retrieve a response.

const res = this.http.post("https://api.com/abcde", {
  test: true,
});

res.subscribe((res) => {
   this.itemID = res.item.id; // I am able to get this ID
});

The second component is B.component.html: This component is responsible for showing/hiding content on a page.

<app-ab-test [showMe]></app-ab-test>

The third component is ab-test.component.ts: This is the actual component used within B.component.html

@Input() public showMe = false;

ab-test.component.html:

<div *ngIf="showMe">
 <img>
</div>

It would be beneficial to connect the this.itemID value to control the boolean value of showMe.

I am still learning and have been able to make it work up to this point. Any guidance you can provide will be greatly appreciated.

Answer №1

To effectively pass data between parent and child components in Angular 4, it is essential to have a good understanding of @Input, @Output, and @ViewChild decorators. Additionally, if you need to send data between two different components that are not related as parent or child, utilizing a Shared Service is recommended.

Discover how to get value from another component in Angular 4

Answer №2

If you need to transfer data using the @Input Decorator, make sure the variable names match:

For instance:

If you are passing data like this:

<app-ab-test [showBanner]="true"></app-ab-test>

then in the ab-test TypeScript file it should be:

@Input() public showBanner;

and the HTML code for ab-test will be:

<div *ngIf="showBanner">
  <img />
</div>

Answer №3

Give this a shot:

-- Add the following code in your Second Component's HTML file
<app-ab-test [showBanner]="showMe"></app-ab-test>

-- Inside your Second Component's TypeScript file
showMe = true;

-- In your Third Component's TypeScript file
@Input() public showBanner;

-- Update your Third Component's HTML file with the following code
<div *ngIf="showBanner">
 <img>
</div>

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