Adding an Interface to Your Provider

Determine which object you want to add the interface to (usually data source, rowset, command, or session objects created by the OLE DB Provider Wizard). It's possible that the object you need to add the interface to is one that your provider doesn't currently support. In that case, run the ATL OLE DB Provider Wizard to create the object. Right-click the project in Class View, click Add > New Item from the menu, select Installed > Visual C++ > ATL, and then click ATL OLEDB Provider. You might want to put the interface code in a separate directory and then copy the files to your provider project.

If you created a new class to support the interface, make the object inherit from that class. For example, you might add the class IRowsetIndexImpl to a rowset object:

template <class Creator>
class CCustomRowset :
    public CRowsetImpl< CCustomRowset<Creator>, CCustomWindowsFile, Creator>,
    public IRowsetIndexImpl< ... >

Add the interface to COM_MAP in the object using the COM_INTERFACE_ENTRY macro. If there's no map, create one. For example:

BEGIN_COM_MAP(CCustomRowset)
     COM_INTERFACE_ENTRY(IRowsetIndex)
END_COM_MAP()

For the rowset object, chain the map of its parent object so that the object can delegate to the parent class. In this example, add the COM_INTERFACE_ENTRY_CHAIN macro to the map:

BEGIN_COM_MAP(CCustomRowset)
     COM_INTERFACE_ENTRY(IRowsetIndex)
     COM_INTERFACE_ENTRY_CHAIN(CRowsetImpl)
END_COM_MAP()

See also

Working with OLE DB Provider Templates