mormot处理multipart

function GetBoundary(const body: string): string;
  //'----------021922143036229'#13#10'Content-Disposition: form-data; name="file"; filename="fg.ini"'
  //'multipart/form-data; boundary=--------021922141024135'
begin
  try
    Result := copy(body, 11, 15);
  except
  end;
end;

function GetMultiPartType(const body: string): string;
begin
  Result := 'multipart/form-data; boundary=--------' + GetBoundary(body);
end;

function upload(url: string; body: TBytes): string;
// /rest/upload
var
  parts: TMultiPartDynArray;
  ss: tstringstream;
  arr: tarray<string>;
  jo: tjsonobject;
  sBody: RawByteString;
begin
  jo := TJSONObject.Create;
  try
    try     //'----------021922143036229'#13#10'Content-Disposition: form-data; name="file"; filename="fg.ini"'
      SetLength(sBody, Length(body));
      Move(body[0], sBody[1], Length(body));
      MultiPartFormDataDecode(GetMultiPartType(sbody), sbody, parts);
      ss := tstringstream.Create(parts[0].Content);
      ForceDirectories(uploadPath);
      arr := url.split(['/']);
      ss.SaveToFile(uploadPath + PathDelim + arr[3]);
      jo.I['status'] := 200;
      jo.S['message'] := 'success';
      Result := jo.ToString;
    except
      on e: Exception do
      begin
        jo.I['status'] := 500;
        jo.S['message'] := 'fail';
        jo.S['exception'] := e.Message;
        Result := jo.ToString;
        writelog('rest.func.upload()' + e.message);
      end;
    end;
  finally
    ss.Free;
    jo.Free;
  end;
end;