How to use this returned IDispatch interface?

[bucher]

Hi,

In my project I want to export an ado connection interface and use it.

The code like this:
STDMETHODIMP CDBInterface::OpenDBConnect(IDispatch **pConnect)
{
_ConnectionPtr pConn;
if (OpenDBConnection(pConn))
{
*pConnect = (IDispatch*)pConn;
pConn->AddRef();
return S_OK;
}else{
return E_FAIL;
}
}

STDMETHODIMP CDBInterface::SQLQueryWitchConn(BSTR sql, IDispatch *pConnect,
IATLRecordset **pRecordSet)
{
CComObject<CATLRecordset>* pClsRecordset = NULL;
HRESULT hr = CComObject<CATLRecordset>::CreateInstance(&pClsRecordset);
if (SUCCEEDED(hr))
{
try{
_ConnectionPtr ptrConn(pConnect);
...
}catch(_com_error& COMErr){
Error((char*)(COMErr.Description()));
hr = E_FAIL;
}
}

return hr;
}

But av exception occurs when I try to create an _ConnectionPtr with returned
IDispatch interface. How can I fix this problem?
Thanks in advanced.

[Scot Brennecke]

A _ConnectionPtr is a smart pointer, and I don't think it wraps anything
that is derived from IDispatch, nor does it have a conversion operator
for IDispatch *. What makes you believe this should be possible?

[Brian Muth]

Scott is correct. A _Connection interface is not an IDispatch interface, so
your attempt to expose this interface in this manner is not possible.
Moreover, I don't believe the _Connection interface can be marshaled.

What is the bigger goal here? Generally speaking, database connections
should be opened late and closed early. They cannot be passed from one
application to another (if that is what you are contemplating).

"bucher" <buc...@xxx.com> wrote in message
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