Ado event model example (VC ++)

This section describes how to instantiate the ADO event model. Below is # ImportA specific example of instantiating the event model in an environment created by a pseudo-command.

Used in general instructionsAdoint. hAs a reference to the method declaration. However# ImportTherefore, some details in the General Instructions need to be slightly changed.

• # ImportPseudoinstructionsTypedef, Method declaration data type and key combination into its basic format.

• All virtual methods that must be overwritten are prefixed with"Raw _".

Some codes only reflect the encoding style.

• AdviseMethod usageIunknownThe pointer is throughQueryInterfaceExplicitly obtained by calling.

• You do not need to explicitly encode the destructor in the class definition.
• Users may need to make the encoding of QueryInterface, addref, and release more reliable.
• _ Uuidof ()The usage of pseudocommands can be extended to get the interface ID.

Finally, this example also contains some practical code.

• This example is written as a console application.

• The comment"// Do some workInsert your own code.
• By default, all event handlers do not perform any operations and cancel further notifications. The user shall insert the appropriate code of the application, and notification should be allowed if necessary.

// eventmodel.cpp : Defines the entry point for the console application.//#import "c:/Program Files/Common Files/System/ADO/msado15.dll" /   no_namespace rename("EOF", "EndOfFile")#include <comdef.h>#include <stdio.h>//----The Connection events----------------------------------------------class CConnEvent : public ConnectionEventsVt{private:        ULONG   m_cRef;    public:        CConnEvent() { m_cRef = 0; };        ~CConnEvent() {};        STDMETHODIMP QueryInterface(REFIID riid, void ** ppv);        STDMETHODIMP_(ULONG) AddRef(void);        STDMETHODIMP_(ULONG) Release(void);        STDMETHODIMP raw_InfoMessage(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection);                STDMETHODIMP raw_BeginTransComplete(             LONG TransactionLevel,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection);          STDMETHODIMP raw_CommitTransComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection);                STDMETHODIMP raw_RollbackTransComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection);                STDMETHODIMP raw_WillExecute(             BSTR *Source,            CursorTypeEnum *CursorType,            LockTypeEnum *LockType,            long *Options,            EventStatusEnum *adStatus,            struct _Command *pCommand,            struct _Recordset *pRecordset,            struct _Connection *pConnection);                STDMETHODIMP raw_ExecuteComplete(             LONG RecordsAffected,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Command *pCommand,            struct _Recordset *pRecordset,            struct _Connection *pConnection);            STDMETHODIMP raw_WillConnect(             BSTR *ConnectionString,            BSTR *UserID,            BSTR *Password,            long *Options,            EventStatusEnum *adStatus,            struct _Connection *pConnection);                STDMETHODIMP raw_ConnectComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection);                STDMETHODIMP raw_Disconnect(             EventStatusEnum *adStatus,            struct _Connection *pConnection);};//-----The Recordset events----------------------------------------------class CRstEvent : public RecordsetEventsVt    {    private:        ULONG m_cRef;       public:        CRstEvent() { m_cRef = 0; };        ~CRstEvent() {};            STDMETHODIMP QueryInterface(REFIID riid, void ** ppv);            STDMETHODIMP_(ULONG) AddRef(void);            STDMETHODIMP_(ULONG) Release(void);            STDMETHODIMP raw_WillChangeField(             LONG cFields,            VARIANT Fields,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_FieldChangeComplete(             LONG cFields,            VARIANT Fields,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_WillChangeRecord(             EventReasonEnum adReason,            LONG cRecords,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_RecordChangeComplete(             EventReasonEnum adReason,            LONG cRecords,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_WillChangeRecordset(             EventReasonEnum adReason,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_RecordsetChangeComplete(             EventReasonEnum adReason,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_WillMove(             EventReasonEnum adReason,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_MoveComplete(             EventReasonEnum adReason,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_EndOfRecordset(             VARIANT_BOOL *fMoreData,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_FetchProgress(             long Progress,            long MaxProgress,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);                STDMETHODIMP raw_FetchComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset);};//-----Implement each connection method----------------------------------        STDMETHODIMP CConnEvent::raw_InfoMessage(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_BeginTransComplete(             LONG TransactionLevel,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_CommitTransComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_RollbackTransComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };            STDMETHODIMP CConnEvent::raw_WillExecute(             BSTR *Source,            CursorTypeEnum *CursorType,            LockTypeEnum *LockType,            long *Options,            EventStatusEnum *adStatus,            struct _Command *pCommand,            struct _Recordset *pRecordset,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_ExecuteComplete(             LONG RecordsAffected,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Command *pCommand,            struct _Recordset *pRecordset,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_WillConnect(             BSTR *ConnectionString,            BSTR *UserID,            BSTR *Password,            long *Options,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_ConnectComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CConnEvent::raw_Disconnect(             EventStatusEnum *adStatus,            struct _Connection *pConnection)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };//-----Implement each recordset method-----------------------------------        STDMETHODIMP CRstEvent::raw_WillChangeField(             LONG cFields,            VARIANT Fields,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_FieldChangeComplete(             LONG cFields,            VARIANT Fields,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_WillChangeRecord(             EventReasonEnum adReason,            LONG cRecords,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_RecordChangeComplete(             EventReasonEnum adReason,            LONG cRecords,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_WillChangeRecordset(             EventReasonEnum adReason,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_RecordsetChangeComplete(             EventReasonEnum adReason,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_WillMove(             EventReasonEnum adReason,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_MoveComplete(             EventReasonEnum adReason,            struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_EndOfRecordset(             VARIANT_BOOL *fMoreData,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_FetchProgress(             long Progress,            long MaxProgress,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };                STDMETHODIMP CRstEvent::raw_FetchComplete(             struct Error *pError,            EventStatusEnum *adStatus,            struct _Recordset *pRecordset)            {            *adStatus = adStatusUnwantedEvent;            return S_OK;            };//-----Implement QueryInterface, AddRef, and Release---------------------    STDMETHODIMP CRstEvent::QueryInterface(REFIID riid, void ** ppv)     {        *ppv = NULL;        if (riid == __uuidof(IUnknown) ||                  riid == __uuidof(RecordsetEventsVt)) *ppv = this;        if (*ppv == NULL)            return ResultFromScode(E_NOINTERFACE);        AddRef();        return NOERROR;    }    STDMETHODIMP_(ULONG) CRstEvent::AddRef(void) { return ++m_cRef; };    STDMETHODIMP_(ULONG) CRstEvent::Release()                                           {                                         if (0 != --m_cRef) return m_cRef;                                        delete this;                                        return 0;                                        }    STDMETHODIMP CConnEvent::QueryInterface(REFIID riid, void ** ppv)             {        *ppv = NULL;        if (riid == __uuidof(IUnknown) ||              riid == __uuidof(ConnectionEventsVt)) *ppv = this;        if (*ppv == NULL)            return ResultFromScode(E_NOINTERFACE);        AddRef();        return NOERROR;    }    STDMETHODIMP_(ULONG) CConnEvent::AddRef() { return ++m_cRef; };    STDMETHODIMP_(ULONG) CConnEvent::Release()                                            {                                         if (0 != --m_cRef) return m_cRef;                                        delete this;                                        return 0;                                        }//-----Write your main block of code-------------------------------------int main(int argc, char* argv[]){    HRESULT hr;    DWORD   dwConnEvt;    DWORD   dwRstEvt;    IConnectionPointContainer   *pCPC = NULL;    IConnectionPoint         *pCP = NULL;    IUnknown               *pUnk = NULL;    CRstEvent               *pRstEvent = NULL;    CConnEvent               *pConnEvent= NULL;    int                     rc = 0;    _RecordsetPtr            pRst;     _ConnectionPtr            pConn;    ::CoInitialize(NULL);        hr = pConn.CreateInstance(__uuidof(Connection));    if (FAILED(hr)) return rc;        hr = pRst.CreateInstance(__uuidof(Recordset));    if (FAILED(hr)) return rc;    // Start using the Connection events    hr = pConn->QueryInterface(__uuidof(IConnectionPointContainer),         (void **)&pCPC);    if (FAILED(hr)) return rc;    hr = pCPC->FindConnectionPoint(__uuidof(ConnectionEvents), &pCP);    pCPC->Release();    if (FAILED(hr)) return rc;    pConnEvent = new CConnEvent();    hr = pConnEvent->QueryInterface(__uuidof(IUnknown), (void **) &pUnk);    if (FAILED(hr)) return rc;    hr = pCP->Advise(pUnk, &dwConnEvt);    pCP->Release();    if (FAILED(hr)) return rc;    // Start using the Recordset events    hr = pRst->QueryInterface(__uuidof(IConnectionPointContainer),         (void **)&pCPC);    if (FAILED(hr)) return rc;    hr = pCPC->FindConnectionPoint(__uuidof(RecordsetEvents), &pCP);    pCPC->Release();    if (FAILED(hr)) return rc;    pRstEvent = new CRstEvent();    hr = pRstEvent->QueryInterface(__uuidof(IUnknown), (void **) &pUnk);    if (FAILED(hr)) return rc;    hr = pCP->Advise(pUnk, &dwRstEvt);    pCP->Release();    if (FAILED(hr)) return rc;    // Do some work    pConn->Open("dsn=Pubs;", "sa", "", adConnectUnspecified);    pRst->Open("SELECT * FROM authors", (IDispatch *) pConn,             adOpenStatic, adLockReadOnly, adCmdText);    pRst->MoveFirst();    while (pRst->EndOfFile == FALSE)    {        wprintf(L"Name = '%s'/n", (wchar_t*)             ((_bstr_t) pRst->Fields->GetItem("au_lname")->Value));        pRst->MoveNext();    }    pRst->Close();    pConn->Close();    // Stop using the Connection events    hr = pConn->QueryInterface(__uuidof(IConnectionPointContainer),         (void **) &pCPC);    if (FAILED(hr)) return rc;    hr = pCPC->FindConnectionPoint(__uuidof(ConnectionEvents), &pCP);    pCPC->Release();    if (FAILED(hr)) return rc;    hr = pCP->Unadvise( dwConnEvt );    pCP->Release();    if (FAILED(hr)) return rc;    // Stop using the Recordset events    hr = pRst->QueryInterface(__uuidof(IConnectionPointContainer),         (void **) &pCPC);    if (FAILED(hr)) return rc;    hr = pCPC->FindConnectionPoint(__uuidof(RecordsetEvents), &pCP);    pCPC->Release();    if (FAILED(hr)) return rc;    hr = pCP->Unadvise( dwRstEvt );    pCP->Release();    if (FAILED(hr)) return rc;    CoUninitialize();    return 1;}