attach file.ts

  attachFile(event: any) {
    const file: File = event.target.files?.[0];
    if (file && this.isValid(file)) {
      this.errorMessage = '';
      const formData = new FormData();
      formData.append('file', file, file.name);
      const uploadFileHeaders = new HttpHeaders({
        Accept: `application/json, text/plain, */*`,
      });
      this.httpClient
        .post('/api/file-upload/upload', formData, {
          headers: uploadFileHeaders,
        })
        .subscribe({
          next: (response) => {
            this.successMessage = `Document ${file.name} is uploaded successfully`;
          },
          error: (error) => {
            this.errorMessage = `failed to upload document.`;
            return error;
          },
        });
    }
  }