get_file_contents_octet_stream_blob

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/http';
import { Observable } from 'rxjs';
import { concatMap } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class TestService {
  constructor(private readonly _http: HttpClient) {}
  // Get text from blob
  blobToText(blob: Blob ) {
    return new Observable(observer => {
      if (!(blob instanceof Blob)) {
        return observer.error(new Error('`blob` must be an instance of Blob.'));
      }
      const reader = new FileReader();
      reader.onerror = err => observer.error(err);
      reader.onabort = err => observer.error(err);
      reader.onload = () => observer.next(reader.result);
      reader.onloadend = () => observer.complete();
      return reader.readAsText(blob);
    });
  }

  // This should return stringified file contents
  getFile(url: string) {
    return this._http.get(url, { responseType: 'blob' })
      .pipe(
        concatMap((blob: Blob) => this.blobToText(blob)),
      );
  }
}