The TInterfacedCollectionItem class is the very base class for many of the schema collection item classes in the DataAbstract library. It represents an interface adapter of the TCollectionItem class. In addition to TCollectionItem functionality, it adds IUknkown interface support that allows to query items to support the given interface.

The TInterfacedCollectionItem class is used as the base for TDAColumnMapping, TDABaseField and TDADriverForeignKey classes.


Instance Methods

QueryInterface  protected stdcall

Returns a reference to a specified interface if the object supports that interface. This is one of the methods introduced by the IUnknown interface.

function QueryInterface(const IID: TGUID; out Obj: ): HResult


  • IID: Identifier of the interface to return
  • Obj: Variable to store the returned interface reference to