First attempt at calling the Angular REST service does not yield any returned value

I currently have 3 components in my Angular application: 1. LeftMenuComponent 2. AppComponent 3. SummaryComponent

Additionally, I have two services - one for making REST calls and another for sharing data among components (RestService, ComponentService).

When selecting an item from the list in LeftMenuComponent, I call the loadService() function which then emits a function contained in the summaryComponent service. This function subscribes to the RestService to fetch and emit data.

Everything is functioning as expected, but I'm facing an issue where I need to click twice for the data to change and reflect in the SummaryComponent on a single click.

I attempted using rxjs/Subscription but encountered the same result.

Here's the code snippet from left-menu-component.html:

<mat-list-item><a routerLink="/summary" (click)="loadService($event, subitem.CATID, subitem.ID)">{{subitem.NAME}}</a></mat-list-item>

And here's the code from Left-Menu-Component.ts:

// TypeScript code here

The Summary-Component HTML code:

//HTML code for SummaryComponent

The corresponding TypeScript code for the SummaryComponent:

// TypeScript code for SummaryComponent

Lastly, the component-service.ts file:

// Code from component-service.ts

And the rest-service.ts file:

// Code from rest-service.ts

No errors reported, only the functionality not working as expected with just one click.

Answer №1

When calling the subscribe method on your observable, it is important to note that it is asynchronous. To ensure proper functionality, be sure to emit your value within the callback function when subscribing. Here's an example:

this.restService.getSummary(CATID,SUBID).subscribe(data => this.change.emit(data));

Additionally, it is recommended to subscribe to your observable in your component rather than directly in the service. This can be achieved without the need for a subject or event emitter.

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