uploadFile(event) {
    const file = event.target.files[0];
    if (this.validateFile(file)) {
      this.isUploadInprogress = true;
      const formData: FormData = new FormData();
      formData.append('files', file, file.name);

      this.uploadService
        .uploadFile(formData)
        .subscribe(
          uploadResponse => this.uploadSuccess(uploadResponse, file),
          error => (this.isUploadInprogress = false)
        );
    } else {
      this.invitationsService.showError('Please upload valid file');
    }
  }