PRB: CDaoRecordView Bookmark Members Invalid After Requery()

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++ 32-bit Edition, versions 4.0, 4.1, 4.1b, 4.2, 4.2b, 5.0, 6.0

SYMPTOMS

In some cases, when you use CDaoRecordView, added records will not show up in the result set after calling Requery() on the CDaoRecordset.

CAUSE

CDaoRecordView uses Jet engine bookmarks to determine when you are on the first or last record of the related CDaoRecordset. Jet engine bookmarks are not guaranteed to be valid following a Requery().

RESOLUTION

To avoid the problem, re-initialize the CDaoRecordView bookmark members to indicate that they are not valid bookmark values following any Requery() on the related CDaoRecordset. The following example shows how this might be done in a CDaoRecordView-derived class's OnMove() function:

   BOOL CMyRecordView::OnMove(UINT nIDMoveCommand)
   {
      CDaoRecordset* pRecordset = OnGetRecordset();
      if (m_bAddMode)
      {
         if (!UpdateData())
            return FALSE;
         try
         {
            pRecordset->Update();
         }
         catch (CDaoException* e)
         {
            AfxMessageBox(e->m_pErrorInfo->m_strDescription);
            e->Delete();
            return FALSE;
         }

         pRecordset->Requery();

         m_varBookmarkCurrent = 1L;   // <<- re-initialize
         m_varBookmarkFirst =         // <<- the bookmark
            m_varBookmarkLast = 0L;   // <<- member variables!

         UpdateData(FALSE);
         m_bAddMode = FALSE;
         return TRUE;
      }
      else
      {
         return CDaoRecordView::OnMove(nIDMoveCommand);
      }
   } 

STATUS

This behavior is by design.

Additional query words:

Keywords : kbusage kbDAO kbDatabase kbMFC kbVC kbVC400 kbVC410 kbVC420 kbVC500 kbVC600
Version : winnt:
Platform : winnt
Issue type : kbprb