How to Compare TBlobField OldValue with Value

Question

In Delphi 2010,

if Field.OldValue <> Field.Value then
...

raises the Exception:

raised exception class EVariantTypeCastError with message 'Could not convert variant of type (Array Byte) into type (Integer)'.

How can I know if a TBlobField value has changed?

Answer 1

I solved the problem with

if Field is TBlobField then
  Result := TBlobField(Field).Modified