Microsoft KB Archive/177911

= OLE2BIN Sample - Storing COleClientItems in a Database =

Article ID: 177911

Article Last Modified on 8/5/2004

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APPLIES TO


 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 5.0 Professional Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition
 * Microsoft Visual C++ .NET 2002 Standard Edition

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This article was previously published under Q177911



SUMMARY
The OLE2BIN sample demonstrates how to save and load an MFC COleClientItem from a Access database (.mdb file). The storage and any COleClientItem data are stored.

STEP2 of the Container tutorial sample was used as the starting point to demonstrate this technique. A Database menu was added, with two submenus, Save Object and Load Object. To save an object to the database, click a COleClientItem to select it and then click Save Object on the Database menu. You will be asked to provide a name for the object, which can then be used later to load the object from the database.

To load an object, click Load Object on the Database menu. You will be asked to select an object that was previously saved. When you first run the sample, there is an object that has already been placed in the 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:

119591 How to Obtain Microsoft Support Files from Online Services

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); }

Additional query words: OLE Field BLOB Binary kbVC500 kbVC600

Keywords: kbdownload kbdatabase kbfile kbsample KB177911

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