🚀 go-pugleaf

Hi,

I have a problem with the ADO components in CBuilder 6 SP4 (German). Some of
my BLOBs get truncated when I try to read the content of the field with
either TADODataSet::CreateBlobStream or TField::Value. I am not really sure
if this is an ADO problem or a problem related to the Borland OleVariant
implementation. The fields of the ADO data set are initialized as
OleVariants. Unfortunately, the constructor of OleVariant uses
SysAllocString to intialize the OleVariant as BSTRs. In contrast to
SysAllocStringByteLen, SysAllocString expects a zero-terminated OLECHAR
string which is not really a good choice for a binary field.
The code I use is something like this:

    TADOConnection* pConnection = new TADOConnection(0);
    pConnection->ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=C:\\Scratch\\db\\franzgaul.xdb;Persist Security Info=False";
    TADODataSet* pDataSet = new TADODataSet(0);
    pDataSet->Connection = pConnection;
    pDataSet->CommandType = cmdText;
    pDataSet->CommandText = "Select * From tblDN Where DID=748";
    pDataSet->Open();
    while(!pDataSet->Eof){
        TMemoryStream* pStream = new TMemoryStream();
        TBlobField* pField = (TBlobField*)pDataSet->FieldByName("docmeta");
        pStream = (TMemoryStream*)pDataSet->CreateBlobStream(pField,bmRead);
        WideString ws = pField->Value;
        int iFieldSize = pField->BlobSize;
        int iMemorySize = pStream->Size;

// NOTE: Both iFieldSize and iMemorySize give the same wrong size.

        delete pStream;
    } // while

Field truncation does not occur with CBuilder 6 SP1.
Is this a known problem and is there a work-around to this? Or am I doing
something wrong?

Thanks,

Thomas