Wt

It matters especially in generating resources from custom model set to WTableView, for example where each resource created slows rendering if resource constructor must access database.

Access to database should be moved to handleRequest to allow generating mime type and suggested file name, for example. Here is a typical usage, that should be:

      void MusicResource::handleRequest(const Wt::Http::Request& request,
          Wt::Http::Response& response)
      {
        if (!request.continuation())
    {
              // here is a access to database moved from constructor (like in http://redmine.webtoolkit.eu/issues/994)
              // we fetch from db a suggestedFileName and ext (extension)
              this->suggestFileName(WString::fromUTF8(suggestedFileName));

              string mimeType = Utils::findContentTypeByExt(ext);
              if (!mimeType.empty())
                this->setMimeType(mimeType);

              if (this->m_generic_wstr.empty())
                this->m_generic_wstr = ZenLib::Ztring(((SyNaT::MIR::SP::SyNaTPGApp::mcs_osid == POCO_OS_WINDOWS_NT ? "\\\\?\\" : "") + Poco::Path(sciezka_do_pliku, Poco::Path::PATH_UNIX).toString()).c_str()).To_Unicode();
            }
            tr->Commit();
          } 
          catch(std::exception &e)
          {
            WApplication::instance()->log("error") << e.what();
          }
        }
        try
        {
          if (!this->m_generic_wstr.empty())
          {
            boost::filesystem::ifstream f(m_generic_wstr, boost::filesystem::ifstream::binary);
            this->handleRequestPiecewise(request, response, f);
          }
        }
        catch(std::exception &e)
        {
          WApplication::instance()->log("error") << e.what();
        }
      }

Hope you will take this into consideration.