Inter - Worked Example

key : purple - original code / blue - new code

Step 1 :

Create a new project using the MFC AppWizard(exe) (this worked example is based on a program called inter). Select Multi Document Application at Step 1 of the Wizard. Set the base class as CListView at the the final step of the Wizard.

Step 2 :

Initialise the OLE/COM libraries. The following code should be added to the InitInstance() function of the App :

BOOL CADOMFC1App::InitInstance()
{

// Add this function to initialize the OLE/COM libraries
AfxOleInit();

The StdAfx.h file should also be adapted as follows (the #import line should be split between three lines as shown below - if this is not done then an illeagal ecape sequence error will occur)

#endif // _AFX_NO_AFXCMN_SUPPORT

#include <comdef.h>

#import "C:\program files\common files\system\ado\msado15.dll" \
no_namespace \
rename( "EOF", "adoEOF" )

Step 3 :

Declare a pointer to the ADO connection object in the Document. Declare a BOOL variable which will indicate whether this object is opened or closed :

// Attributes
public:
BOOL m_IsConnectionOpen;
_ConnectionPtr m_pConnection;

note: (Initialise the BOOL variable to FALSE in the document's constructor)

Step 4 :

Open the database by adding code to the OnNewDocument() function in the Document. Ensure the file path is correct for the data source!

BOOL CInterDoc::OnNewDocument()
{

if (!CDocument::OnNewDocument())
return FALSE;

HRESULT hr;


hr = m_pConnection.CreateInstance( __uuidof( Connection ) );
if (SUCCEEDED(hr))
{

hr = m_pConnection->Open(
_bstr_t(L"Provider=Microsoft.Jet.OLEDB.3.51;Data Source=c:\\myfiles\\access\\names.mdb;"),
_bstr_t(L""),
_bstr_t(L""),
adModeUnknown);
if (SUCCEEDED(hr))
{

m_IsConnectionOpen = TRUE;

}

}

return TRUE;

}

Step 5 :

Ensure the Access file is closed by doing so automatically in the Document. Use the ClassWizard to add the following function :

void CInterDoc::OnCloseDocument()
{

// if when the document closes the connection is still open
// this function will close it automatically

if (m_IsConnectionOpen)
{

m_IsConnectionOpen = FALSE;
m_pConnection->Close();

}

CDocument::OnCloseDocument();

}

Step 6 :

Add the exception handling code to the OnNewDocument() function in the Document.

BOOL CInterDoc::OnNewDocument()
{

if (!CDocument::OnNewDocument())
return FALSE;

HRESULT hr;

try
{

hr = m_pConnection.CreateInstance( __uuidof( Connection ) );
if (SUCCEEDED(hr))
{

hr = m_pConnection->Open(
_bstr_t(L"Provider=Microsoft.Jet.OLEDB.3.51;Data Source=c:\\myfiles\\access\\names.mdb;"),
_bstr_t(L""),
_bstr_t(L""),
adModeUnknown);
if (SUCCEEDED(hr))
{

AfxMessageBox("THE SPECIFIED DATABASE HAS BEEN ACCESSED!!!");
m_IsConnectionOpen = TRUE;

}

}

}
catch( _com_error &e )
{

AfxMessageBox("FAILED - SEE DEBUG INFO!!!");
// Get info from _com_error
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
TRACE( "\nException thrown for classes generated by #import" );
TRACE( "\n\tCode = %081x", e.Error());
TRACE( "\n\tCode meaning = %s", e.ErrorMessage());
TRACE( "\n\tSource = %s", (LPCTSTR) bstrSource);
TRACE( "\n\tDescription = %s\n", (LPCTSTR) bstrDescription);

}
catch(...)
{

AfxMessageBox("FAILED - SEE DEBUG INFO!!!");
TRACE( "*** Unhandled Exception ***" );

}

return TRUE;

}

Step 7 :

Import three files from the MSDN sample DAOVIEW into the project - these will handle the ListCtrl format. These may be downloaded here. The StdAfx.h file needs the following code added :

#include <afxcview.h>
#include "ctrlext.h"

Step 8 :

Using ClassWizard add an OnCreate() function to the View :

int CInterView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{

lpCreateStruct->style |= LVS_REPORT;
if (CListView::OnCreate(lpCreateStruct) == -1)
return -1;

// TODO: Add your specialized creation code here

return 0;

}

Step 9 :

Insert some example data in the Views OnInitialUpdate() function :

void CInterView::OnInitialUpdate()
{

CListView::OnInitialUpdate();


CListCtrlEx& ctlList = (CListCtrlEx&) GetListCtrl();

ctlList.AddColumn(" First Test Column ", 0);
ctlList.AddColumn(" Second Test Column ", 1);
ctlList.AddColumn(" Third Test Column ", 3);

ctlList.AddItem(0, 0, "First Test Row");
ctlList.AddItem(1, 0, "Second Test Row")

}

Step 10 :

Using ClassWizard add a OnRButtonDown() function - the main data processing here. This is shown in the code below :

void CInterView::OnRButtonDown(UINT nFlags, CPoint point)
{

_RecordsetPtr pRecordSet;
CInterDoc * pDoc;
pDoc = GetDocument();

// the SQL query is below
_bstr_t bstrQuery("SELECT * FROM names ORDER BY SecondName");

_variant_t vRecsAffected(0L);

try
{

pRecordSet = pDoc->m_pConnection->Execute(bstrQuery, &vRecsAffected, adOptionUnspecified);

if (!pRecordSet->GetadoEOF())
{

CListCtrlEx& ctlList = (CListCtrlEx&) GetListCtrl();
ctlList.DeleteAllItems();
while(ctlList.DeleteColumn(0));

ctlList.AddColumn("Second Name ",0);
ctlList.AddColumn("Title ",1);
ctlList.AddColumn("First Name ",2);

int i = 0;
_variant_t vSecondName;
_variant_t vTitle;
_variant_t vFirstName;
while (!pRecordSet->GetadoEOF())
{

vSecondName = pRecordSet->GetCollect(L"SecondName");
ctlList.AddItem(i,0,(_bstr_t) vSecondName);
vTitle = pRecordSet->GetCollect(L"Title");
ctlList.AddItem(i,1,(_bstr_t) vTitle);
vFirstName = pRecordSet->GetCollect(L"FirstName");
ctlList.AddItem(i,2,(_bstr_t) vFirstName);
i++;
pRecordSet->MoveNext();

}

}

pRecordSet->Close();

}
catch( _com_error &e )
{

AfxMessageBox("FAILED - SEE DEBUG INFO!!!");
// Get info from _com_error
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
TRACE( "\nException thrown for classes generated by #import" );
TRACE( "\n\tCode = %081x", e.Error());
TRACE( "\n\tCode meaning = %s", e.ErrorMessage());
TRACE( "\n\tSource = %s", (LPCTSTR) bstrSource);
TRACE( "\n\tDescription = %s\n", (LPCTSTR) bstrDescription);

}
catch(...)
{

AfxMessageBox("FAILED - SEE DEBUG INFO!!!");
TRACE( "*** Unhandled Exception ***" );

}

CListView::OnRButtonDown(nFlags, point);

}

Click here for the basic exercise

Click here for the source code

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