Property Example
The code in this example shows how to get the value of a property and how to add properties to a rowset.
/////////////////////////////////////////////////////////////////
// myGetProperty
//
// This function gets the BOOL value for the specified property
// and returns the result in *pbValue.
//
/////////////////////////////////////////////////////////////////
HRESULT myGetProperty
(
IUnknown * pIUnknown,
REFIID riid,
DBPROPID dwPropertyID,
REFGUID guidPropertySet,
BOOL * pbValue
)
{
HRESULT hr;
DBPROPID rgPropertyIDs[1];
DBPROPIDSET rgPropertyIDSets[1];
ULONG cPropSets = 0;
DBPROPSET * rgPropSets = NULL;
IDBProperties * pIDBProperties = NULL;
ISessionProperties * pISesProps = NULL;
ICommandProperties * pICmdProps = NULL;
IRowsetInfo * pIRowsetInfo = NULL;
// Initialize the output value
*pbValue = FALSE;
// Set up the property ID array
rgPropertyIDs[0] = dwPropertyID;
// Set up the Property ID Set
rgPropertyIDSets[0].rgPropertyIDs = rgPropertyIDs;
rgPropertyIDSets[0].cPropertyIDs = 1;
rgPropertyIDSets[0].guidPropertySet = guidPropertySet;
// Get the property value for this property from the provider, but
// don't try to display extended error information, since this may
// not be a supported property: a failure is, in fact, expected if
// the property is not supported
if( riid == IID_IDBProperties )
{
XCHECK_HR(hr = pIUnknown->QueryInterface(IID_IDBProperties,
(void**)&pIDBProperties));
CHECK_HR(hr = pIDBProperties->GetProperties(
1, //cPropertyIDSets
rgPropertyIDSets, //rgPropertyIDSets
&cPropSets, //pcPropSets
&rgPropSets //prgPropSets
));
}
else if( riid == IID_ISessionProperties )
{
XCHECK_HR(hr = pIUnknown->QueryInterface(IID_ISessionProperties,
(void**)&pISesProps));
CHECK_HR(hr = pISesProps->GetProperties(
1, //cPropertyIDSets
rgPropertyIDSets, //rgPropertyIDSets
&cPropSets, //pcPropSets
&rgPropSets //prgPropSets
));
}
else if( riid == IID_ICommandProperties )
{
XCHECK_HR(hr = pIUnknown->QueryInterface(IID_ICommandProperties,
(void**)&pICmdProps));
CHECK_HR(hr = pICmdProps->GetProperties(
1, //cPropertyIDSets
rgPropertyIDSets, //rgPropertyIDSets
&cPropSets, //pcPropSets
&rgPropSets //prgPropSets
));
}
else
{
XCHECK_HR(hr = pIUnknown->QueryInterface(IID_IRowsetInfo,
(void**)&pIRowsetInfo));
CHECK_HR(hr = pIRowsetInfo->GetProperties(
1, //cPropertyIDSets
rgPropertyIDSets, //rgPropertyIDSets
&cPropSets, //pcPropSets
&rgPropSets //prgPropSets
));
}
// Return the value for this property to the caller if
// it's a VT_BOOL type value, as expected
if( V_VT(&rgPropSets[0].rgProperties[0].vValue) == VT_BOOL )
*pbValue = V_BOOL(&rgPropSets[0].rgProperties[0].vValue);
CLEANUP:
if( rgPropSets )
{
CoTaskMemFree(rgPropSets[0].rgProperties);
CoTaskMemFree(rgPropSets);
}
if( pIDBProperties )
pIDBProperties->Release();
if( pISesProps )
pISesProps->Release();
if( pICmdProps )
pICmdProps->Release();
if( pIRowsetInfo )
pIRowsetInfo->Release();
return hr;
}
/////////////////////////////////////////////////////////////////
// myAddProperty
//
// This function initializes the property structure pProp
//
/////////////////////////////////////////////////////////////////
void myAddProperty
(
DBPROP * pProp,
DBPROPID dwPropertyID,
VARTYPE vtType,
LONG lValue,
DBPROPOPTIONS dwOptions
)
{
// Set up the property structure
pProp->dwPropertyID = dwPropertyID;
pProp->dwOptions = dwOptions;
pProp->dwStatus = DBPROPSTATUS_OK;
pProp->colid = DB_NULLID;
V_VT(&pProp->vValue) = vtType;
// Since VARIANT data is a union, we can place the value in any
// member (except for VT_DECIMAL, which is a union with the whole
// VARIANT structure -- but we know we're not passing VT_DECIMAL)
V_I4(&pProp->vValue) = lValue;
}