Angular 5 http GET images from back end

Question

I have an Angular 5 project.

I need to display images in the UI that are fetched from the back end (say for example I want to display users' avatars in the upper toolbar, like in the SO toolbar above).

The back end is a REST server that serves images when invoked on some end-point.

I cannot seem to GET the images from the back end. And I am sure that the back end works.

I have try to do the following (based on this article):

Here is my service image.service.ts (boiler plate has been removed)

getImage(url: string): Observable<Blob> {
  return this.httpClient.get(`${url}`, {responseType: 'blob'})
}

Here is my coponent image.component.ts

@Component({
  selector: 'app-image',
  templateUrl: './image.component.html',
  styleUrls: ['./image.component.css']
})
export class ImageComponent implements OnInit {
  @ViewChild('myImage') image: ElementRef

  constructor(private imageService: ImageService) {}

  ngOnInit() {
    this.getMyImage('http://my-super-host:3000/images/super-hero.png')
  }

  getMyImage(url: string): void {
    this.imageService.getImage(url)
      .subscribe(response => this.image.nativeElement.src = window.URL.createObjectURL(response))
  }
}

And eventually, here is my image.component.html

<img #myImage>

In the browser's console, there is an error message saying that

ERROR TypeError: _this.image is undefined

This solution doesn't work. What am I missing here?

Alternatively, you could use base64 string as the image. Something like this: stackoverflow.com/a/8499716/193634 — Rosdi Kasim
– Rosdi Kasim, Commented Mar 21, 2018 at 16:30
@Jeremy Thille because I haven't met you before? No, seriously, is it secure to do so? — avi.elkharrat
– avi.elkharrat, Commented Mar 21, 2018 at 16:42
Is the img tag rendered conditionally, eg. inside an *ngIf ? That's the most common reason why ViewChild doesn't work, because the element doesn't exist at component init time. A [src] binding might do it. — funkizer
– funkizer, Commented Mar 21, 2018 at 16:44

avi.elkharrat · Accepted Answer · 2018-05-02 13:54:23Z

1

Adding a simple

<img src={{url}}>

did the trick.

From then, you may add *ngIf, class, alt... as needed.

answered May 2, 2018 at 13:54

avi.elkharrat

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user2367418 · Accepted Answer · 2020-05-27 00:41:56Z

0

Another slightly different solution by someone else is discussed at:

[https://medium.com/techinpieces/blobs-with-http-post-aand-angular-5-a-short-story-993084811af4][1]

Based on that, I wrote code that works with Angular 7, some of which is below. See the link above for more info.

 getBlob_withQueryParams(imageUrl: string, params: HttpParams):  Rxjs.Observable<Blob> {
     const headers = new HttpHeaders({
       'Content-Type': 'application/json',
       'Accept': 'application/json'
     });
    return this._http.get<Blob>(imageUrl, {headers: headers, params: params, responseType: 'blob' as 'json' });
  }

answered May 27, 2020 at 0:41

user2367418

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