OLE2BIN Sample - Storing COleClientItems in a Database

MORE INFORMATION

The following files are available for download from the Microsoft Download Center:


Ole2bin.exe

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.

The core functionality of the sample is located in two functions, CContainerView::OnDatabaseLoad() and CContainerView::OnDatabaseSave().

Below is the code for the OnDatabaseSave() function. The only item that is not well documented is the m_bForceFlat member. This member tells the archive to store the data without creating additional substorages. All the data is saved into the one stream.

NOTE: Because the COleClientItem is serialized, not only is the OLE storage saved, but all of the COleClientItem's data (position, display aspect, and so on) is also saved.

Here is the OnDatabaseSave() method:

   static const TCHAR szContents[] = _T("Contents");
   #define INITIAL_ALLOC_SIZE 100000

   void CContainerView::OnDatabaseSave()
   {
      LPLOCKBYTES pLockBytes = NULL;
      LPSTORAGE pStorage = NULL;

      ASSERT(m_pSelection != NULL);

      CNameDlg dlg;
      if (dlg.DoModal() == IDCANCEL || dlg.m_Name == "")
      {
         return;
      }

      CDatabase db;
      if (!db.OpenEx("DRIVER=Microsoft Access Driver
         (*.mdb);DBQ=BinDB.MDB;FIL=MS Access for Microsoft
         Access;UID=Admin;PWD=;"))
      {
         AfxMessageBox("Access ODBC Driver not installed");
         return;
      }

      CObjectSet rs(&db);
      rs.Open();
      rs.AddNew();

      rs.m_Name = dlg.m_Name;

      GlobalFree(rs.m_OleObject.m_hData);

      rs.m_OleObject.m_hData = GlobalAlloc(GMEM_MOVEABLE,
         INITIAL_ALLOC_SIZE);

      if (FAILED(CreateILockBytesOnHGlobal(rs.m_OleObject.m_hData,FALSE,
                   &pLockBytes)))
      {
         AfxMessageBox("Unable to retrieve LockBytes");
         return;
      }

      if (FAILED(StgCreateDocfileOnILockBytes(pLockBytes, STGM_DIRECT |
              STGM_CREATE | STGM_READWRITE | STGM_SHARE_EXCLUSIVE, 0,
              &pStorage)))
      {
        AfxMessageBox("Failure creating storage on LockBytes");
        pLockBytes->Release();
        return;
      }

      COleStreamFile file;
      CFileException fe;
      if (!file.CreateStream(pStorage, szContents,
            CFile::modeReadWrite|CFile::shareExclusive|CFile::modeCreate,
            &fe))
      {
        AfxThrowFileException(fe.m_cause, fe.m_lOsError);
      }

      // save to Contents stream
      CArchive saveArchive(&file, CArchive::store |
                             CArchive::bNoFlushOnDelete);
      saveArchive.m_pDocument = GetDocument();
      saveArchive.m_bForceFlat = TRUE;

      TRY
      {
          m_pSelection->Serialize(saveArchive);
          saveArchive.Close();
          file.Close();

          // commit the storage
          SCODE sc = pStorage->Commit(STGC_ONLYIFCURRENT);
          if (sc != S_OK)
            AfxThrowOleException(sc);
      }
      CATCH_ALL(e)
      {
          file.Abort();   // will not throw an exception
          THROW_LAST();
      }
      END_CATCH_ALL


      rs.SetFieldDirty(&rs.m_OleObject);
      rs.SetFieldNull(&rs.m_OleObject, FALSE);

      STATSTG statstg;
      pLockBytes->Stat(&statstg,  STATFLAG_NONAME);
      rs.m_OleObject.m_dwDataLength = statstg.cbSize.LowPart;

      rs.Update();
      rs.Close();

      pLockBytes->Release();
      pStorage->Release();
   }
				

Here is the OnDatabaseLoad() method, which is just the opposite of the OnDatabaseSave() method:

   void CContainerView::OnDatabaseLoad()
   {
      LPSTORAGE pStorage = NULL;
      LPLOCKBYTES pLockBytes = NULL;

      // Make certain there are objects in the database
      // If there are, bring up dialog for user to select an object
      CDatabase db;
      if (!db.OpenEx("DRIVER=Microsoft Access Driver
         (*.mdb);DBQ=BinDB.MDB;FIL=MS Access for Microsoft
         Access;UID=Admin;PWD=;"))
      {
         AfxMessageBox("Access ODBC Driver not installed");
         return;
      }

      CObjNameSet rsObjName(&db);

      rsObjName.Open();
      if (rsObjName.IsEOF())
      {
          rsObjName.Close();
          AfxMessageBox("No objects exist in the database.");
          return;
      }

      CObjDlg dlg(&rsObjName);
      if (dlg.DoModal() == IDCANCEL)
      {
         return;
      }

      rsObjName.Close();

      CObjectSet rs(&db);

      CContainerItem * pItem = new CContainerItem;

      rs.m_strFilter = "Name = '" + dlg.m_ObjectName + "'";

      rs.Open();

      if (FAILED(CreateILockBytesOnHGlobal(rs.m_OleObject.m_hData, FALSE,
                    &pLockBytes)))
      {
          AfxMessageBox("Unable to retrieve LockBytes");
          return;
      }

      HRESULT hr = StgOpenStorageOnILockBytes(pLockBytes, NULL,
                    STGM_DIRECT | STGM_READ | STGM_SHARE_EXCLUSIVE  , NULL,
                    0, &pStorage);

      if (FAILED(hr))
      {
         AfxMessageBox("Failure opening storage");
         pLockBytes->Release();
         return;
      }


      COleStreamFile file;
      CFileException fe;
      if (!file.OpenStream(pStorage, szContents,
             CFile::modeRead|CFile::shareExclusive, &fe))
      {
         if (fe.m_cause == CFileException::fileNotFound)
            AfxThrowArchiveException(CArchiveException::badSchema);
         else
            AfxThrowFileException(fe.m_cause, fe.m_lOsError);
      }

      CArchive loadArchive(&file, CArchive::load |
                           CArchive::bNoFlushOnDelete);
      loadArchive.m_pDocument = GetDocument();
      loadArchive.m_bForceFlat = TRUE;

      TRY
      {
         pItem->Serialize(loadArchive);     // load main contents
         loadArchive.Close();
         file.Close();
      }
      CATCH_ALL(e)
      {
         file.Abort();   // will not throw an exception
         // remove item because it didn't fully loaded
         GetDocument()->RemoveItem(pItem);
         THROW_LAST();
      }
      END_CATCH_ALL

      rs.Close();

      db.Close();

      pLockBytes->Release();

      GetDocument()->UpdateAllViews(NULL);
   }