Revit API Fun: FamDoc.FamilyManager.SetFormula() Throws Exception!

Based on our experiences in the past decades, it’s fun to play with Revit API. Here is one.

Family parameter can be added to family without types through API; but its formula cannot be set! The method call FamDoc.FamilyManager.SetFormula(...) would throw out an exception.

'There is no valid family type.'

Fortunately, Revit UI allows us to do so!

Enjoy!