DOCUMENT:Q125727  23-JUL-2001  [visualc]
TITLE   :FIX: Text Truncated When Using Dynaset and RFX_Text()
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:
OPER/SYS:
KEYWORDS:kbDatabase kbMFC kbODBC kbVCkbbuglist kbfixlist

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

 - The Microsoft Foundation Classes (MFC), included with:
    - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, version 2.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When editing a record with a text field, the text gets truncated to the length
of the previous value. For example, if a text field has the value "ABC" and an
application attempts to change the value to "TEST," the result is "TES."

This occurs when opening a CRecordset with CRecordset::dynaset as the first
argument of CRecordset::Open() and using RFX_Text() to map the field to a
CRecordset member variable.

CAUSE
=====

The CFieldExchange::Default() function, located in \MSVC20\MFC\SRC\DBRFX.CPP,
contains the following code:

   case BindFieldForUpdate:
      if (!m_prs->IsFieldFlagDirty(nField, m_nFieldType))
      {
        // If field is not dirty, set bound length to SQL_IGNORE
        // for SQLSetPos updates
        *plLength = SQL_IGNORE;
      }
      else if ((m_prs->m_nEditMode == CRecordset::addnew) &&
              (!m_prs->IsFieldFlagNull(nField, m_nFieldType)))
      {
        // plLength always set to SQL_NULL_DATA in AddNew mode
        *plLength = cbValue;
      }
      return;

The second If statement shouldn't check for only CRecordset::addnew because this
also applies to updates.

RESOLUTION
==========

To work around this problem, perform these steps:

1. In one of your header files, perhaps in your CRecordset's header file, create
   the following function prototype:

       void RFX_Text2(CFieldExchange* pFX, const char *szName,
          CString& value, int nMaxLength=255, int nColumnType=SQL_VARCHAR);

2. In your CRecordset's .CPP file or elsewhere, add the RFX_Text2() definition
   shown below:

      ****
      void RFX_Text2(CFieldExchange* pFX, const char *szName,
                     CString& value, int nMaxLength, int nColumnType)
      {
        ASSERT(AfxIsValidAddress(pFX, sizeof(CFieldExchange)));
        ASSERT(AfxIsValidString(szName));
        ASSERT(AfxIsValidAddress(&value, sizeof(CString)));

        if (pFX->m_nOperation==CFieldExchange::BindFieldForUpdate)
        {
          UINT nField;
          if (!pFX->IsFieldType(&nField))
            return;

       LONG* plLength = pFX->m_prs->GetFieldLength(pFX);

       if (!pFX->m_prs->IsFieldFlagDirty(nField, pFX->m_nFieldType))
       {
         // If field is not dirty, set bound length to SQL_IGNORE
         // for SQLSetPos updates
         *plLength = SQL_IGNORE;
       }
       else if (!pFX->m_prs->IsFieldFlagNull(nField, pFX->m_nFieldType))
       {
         // plLength always set to SQL_NULL_DATA in AddNew mode
         *plLength = value.GetLength();
       }
       return;
        }

        RFX_Text(pFX, szName,value, nMaxLength,nColumnType);
      }

      ****

3. Modify the DoFieldExchange member function of your CRecordset class,
   replacing calls to RFX_Text with calls to the RFX_Text2 function described
   above.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 2.1.

Additional query words: 2.00 3.00

======================================================================
Keywords          : kbDatabase kbMFC kbODBC kbVC kbbuglist kbfixlist
Technology        : kbAudDeveloper kbMFC
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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