Re: How to use this returned IDispatch interface?

Scot Brennecke <>
Fri, 27 Nov 2009 23:47:40 -0600
bucher wrote:


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;
    return S_OK;
   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))
    _ConnectionPtr ptrConn(pConnect);
   }catch(_com_error& COMErr){
    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.

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?

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