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Q143408: FIX: Assertion Failure After Using CDaoWorkspace::Create()

Article: Q143408
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,4.1; :
Operating System(s): 
Keyword(s): kbDAOsearch kbDatabase kbMFC kbVC
Last Modified: 03-AUG-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual C++, versions 4.0, 4.1 
- Microsoft Foundation Classes (MFC) 
-------------------------------------------------------------------------------

SYMPTOMS
========

Using a CDaoWorkspace object after calling the CDaoWorkspace::Create() function
may cause an assertion failure in Daocore.cpp line 651 inside the
CDaoWorkspace::Open() function.

CAUSE
=====

When a newly created CDaoWorkspace object is used for the first time, the
CDaoWorkspace::Open() function is called. This function should only be called to
retrieve either a named workspace or the default workspace from the workspaces
collection.

MFC relies on the value of the m_bOpen member variable to determine if the
workspace object's Open() function needs to be called. This member variable is
set to TRUE only inside the Open() and Append() member functions.

RESOLUTION
==========

Call CDaoWorkspace::Append() before using a newly created workspace object.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was corrected in Visual C++, 32-bit
Edition, version 4.2.

MORE INFORMATION
================

Sample Code
-----------

  CDaoWorkspace wsp;
  wsp.Create(_T("NewWorkspace"), _T("admin"), _T(""));
  // Call Append() to set the m_bOpen flag.
  // This will also append the workspace to the engine's workspaces
  // collection
  wsp.Append();

  CDaoDatabase db(&wsp);
  db.Open(_T("c:\\path\\to\\mdbfile.mdb"), FALSE, FALSE, NULL);
  ...

Additional query words: kbVC400bug 4.00 4.10 vcfixlist420

======================================================================
Keywords          : kbDAOsearch kbDatabase kbMFC kbVC 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbMFC kbVC410
Version           : winnt:4.0,4.1; :
Issue type        : kbbug
Solution Type     : kbfix

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