Angular 5 download excel file with post request

I struggle with this one all day. Replace angular HttpClient and use XMLHttpRequest as follows:

var oReq = new XMLHttpRequest();
  oReq.open("POST", url, true);
  oReq.setRequestHeader("content-type", "application/json");
  oReq.responseType = "arraybuffer";

  oReq.onload = function (oEvent) {
    var arrayBuffer = oReq.response;
    if (arrayBuffer) {
      var byteArray = new Uint8Array(arrayBuffer);
      console.log(byteArray, byteArray.length);
      this.downloadFile(byteArray, 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'export.xlsx');
    }
  };

  oReq.send(body);

Then modified the creation of the Blob in your downloadFile function:

const url = window.URL.createObjectURL(new Blob([binaryData]));

In your case the service will look something like this:

DownloadData(model:requiredParams):Observable<any>{
  return new Observable(obs => {
    var oReq = new XMLHttpRequest();
    oReq.open("POST", url, true);
    oReq.setRequestHeader("content-type", "application/json");
    oReq.responseType = "arraybuffer";

    oReq.onload = function (oEvent) {
      var arrayBuffer = oReq.response;
      var byteArray = new Uint8Array(arrayBuffer);
      obs.next(byteArray);
    };

    const body = JSON.stringify(model);
    oReq.send(body);
  });
}

Then the component:

exportToExcel() {
  this.loadingOverlayFlag = true;
  this.podashboardService.DownloadData(this.data).subscribe(result=>{
    // console.log(result);
    this.downloadFile(result,'application/vnd.openxmlformats-
    officedocument.spreadsheetml.sheet', 'export.xlsx');
  })
}

downloadFile(blob: any, type: string, filename: string) {

  var binaryData = [];
  binaryData.push(blob);

  const url = window.URL.createObjectURL(new Blob(binaryData, { type: filetype })); // <-- work with blob directly

   // create hidden dom element (so it works in all browsers)
   const a = document.createElement('a');
   a.setAttribute('style', 'display:none;');
   document.body.appendChild(a);

   // create file, attach to hidden element and open hidden element
   a.href = url;
   a.download = filename;
   a.click();
}

I managed to make it working by using httpClient ( responseType: 'arraybuffer' in the httpOptions did the trick).

createReportBackend() {

    const httpOption: Object = {
      observe: 'response',
      headers: new HttpHeaders({
        'Content-Type': 'application/json'
      }),
      responseType: 'arraybuffer'
    };

    this.httpClient.post('http://localhost:8080/api/report', this.data, httpOption)
      .pipe(map((res: HttpResponse) => {
        return {
          filename: 'Drinks.xlsx',
          data: new Blob(
            [res['body']],
            { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'}
          ),
        };
      }))
      .subscribe(res => {
        if (window.navigator.msSaveOrOpenBlob) {
          window.navigator.msSaveBlob(res.data, res.filename);
        } else {
          const link = window.URL.createObjectURL(res.data);
          const a = document.createElement('a');
          document.body.appendChild(a);
          a.setAttribute('style', 'display: none');
          a.href = link;
          a.download = res.filename;
          a.click();
          window.URL.revokeObjectURL(link);
          a.remove();
        }
      }, error => {
        throw error;
      }, () => {
        console.log('Completed file download.');
      });
  }