Angular: How to download a file from HttpClient?

I need download an excel from my backend, its returned a file.

When I do the request I get the error:

TypeError: You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.

My code is:

this.http.get(`${environment.apiUrl}/...`)
      .subscribe(response => this.downloadFile(response, "application/ms-excel"));

I tried get and map(...) but didn't work.

Details: angular 5.2

references:

import { HttpClient } from '@angular/common/http';
import 'rxjs/add/observable/throw';
import 'rxjs/add/operator/finally';
import 'rxjs/add/operator/map'
import 'rxjs/add/operator/catch';

Content-Type of response:

Content-Type: application/ms-excel

What's wrong?

Solution 1:

Blobs are returned with file type from backend. The following function will accept any file type and popup download window:

downloadFile(route: string, filename: string = null): void{

    const baseUrl = 'http://myserver/index.php/api';
    const token = 'my JWT';
    const headers = new HttpHeaders().set('authorization','Bearer '+token);
    this.http.get(baseUrl + route,{headers, responseType: 'blob' as 'json'}).subscribe(
        (response: any) =>{
            let dataType = response.type;
            let binaryData = [];
            binaryData.push(response);
            let downloadLink = document.createElement('a');
            downloadLink.href = window.URL.createObjectURL(new Blob(binaryData, {type: dataType}));
            if (filename)
                downloadLink.setAttribute('download', filename);
            document.body.appendChild(downloadLink);
            downloadLink.click();
        }
    )
}

Solution 2:

Try something like this:

type: application/ms-excel

/**
 *  used to get file from server
 */

this.http.get(`${environment.apiUrl}`,{
          responseType: 'arraybuffer',headers:headers} 
         ).subscribe(response => this.downLoadFile(response, "application/ms-excel"));


    /**
     * Method is use to download file.
     * @param data - Array Buffer data
     * @param type - type of the document.
     */
    downLoadFile(data: any, type: string) {
        let blob = new Blob([data], { type: type});
        let url = window.URL.createObjectURL(blob);
        let pwa = window.open(url);
        if (!pwa || pwa.closed || typeof pwa.closed == 'undefined') {
            alert( 'Please disable your Pop-up blocker and try again.');
        }
    }

Solution 3:

It took me a while to implement the other responses, as I'm using Angular 8 (tested up to 10). I ended up with the following code (heavily inspired by Hasan).

Note that for the name to be set, the header Access-Control-Expose-Headers MUST include Content-Disposition. To set this in django RF:

http_response = HttpResponse(package, content_type='application/javascript')
http_response['Content-Disposition'] = 'attachment; filename="{}"'.format(filename)
http_response['Access-Control-Expose-Headers'] = "Content-Disposition"

In angular:

  // component.ts
  // getFileName not necessary, you can just set this as a string if you wish
  getFileName(response: HttpResponse<Blob>) {
    let filename: string;
    try {
      const contentDisposition: string = response.headers.get('content-disposition');
      const r = /(?:filename=")(.+)(?:;")/
      filename = r.exec(contentDisposition)[1];
    }
    catch (e) {
      filename = 'myfile.txt'
    }
    return filename
  }

  
  downloadFile() {
    this._fileService.downloadFile(this.file.uuid)
      .subscribe(
        (response: HttpResponse<Blob>) => {
          let filename: string = this.getFileName(response)
          let binaryData = [];
          binaryData.push(response.body);
          let downloadLink = document.createElement('a');
          downloadLink.href = window.URL.createObjectURL(new Blob(binaryData, { type: 'blob' }));
          downloadLink.setAttribute('download', filename);
          document.body.appendChild(downloadLink);
          downloadLink.click();
        }
      )
  }

  // service.ts
  downloadFile(uuid: string) {
    return this._http.get<Blob>(`${environment.apiUrl}/api/v1/file/${uuid}/package/`, { observe: 'response', responseType: 'blob' as 'json' })
  }