The button click function is failing to trigger in Angular

Within my .html file, the following code is present: The button labeled Data Import is displayed....

<button mat-menu-item (click)="download()">
                <mat-icon>cloud_download</mat-icon>
                <span>Data Import</span>
</button>

In the component.ts file:
I have defined a function that should be executed upon clicking the button:

  constructor(
           private downloadService: DownloadService
      )

    download(){
      this.downloadService.getDownload();

      }

In the downloadservice.ts file:

A service has been created to make a backend API call to /Download.

 export class DownloadService {
     etext : String;
    baseUrl: string = environment.apiUrl + '/Download';
      constructor(private http: HttpClient) { }

      getDownload() {
        return this.http.get(this.baseUrl);
        this.etext="The operation has been done";
      }
      }

When attempting to click on the Data Import button, no action is triggered and no event is recorded.

Answer №1

1- The first line will not be executed due to the presence of a return keyword in the preceding statement:

return this.http.get(this.baseUrl);
this.etext="The task has been completed";

2- According to Martin Čuka's input, it is necessary to subscribe to the Observable returned by httpclient.

this.downloadService.getDownload().subscribe(resp => { // perform actions });

Answer №2

In order for something to happen, you need to subscribe to the Observable returned by httpClient. Make sure to add a subscribe method to your service.

this.downloadService.getDownload().subscribe();

Regarding the line:

this.etext="The operation has been done";

The compiler may warn you that it is unreachable, but the actual issue lies in not including the subscribe method.

Answer №3

export class DownloadComponent {
  constructor(private downloadService: DownloadService){}

  initiateDownload(){
    this.downloadService.initiateDownloadRequest().subscribe(
      () => {
        // handle successful download
      },
      (error) => {
        // handle error during download
      }
    );
  }
}

Answer №4

It seems like the http request has been triggered, but without subscribing to the Observable returned by http.get, you won't know when it completes.

component.ts

class Component {

  constructor(private downloadService: DownloadService){}

    download(){
      this.downloadService.getDownload().subscribe(
        () => {
          // handle success
        },
        (error) => {
         // handle error
        }
      );
    }
}

Remember to unsubscribe from subscriptions once they are no longer needed. Read more about unsubscribing here

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