Difference between FamilySymbol and ElementType?

[garrett]

Both FamilySymbol and ElementType seem to represent the same idea.  What is the difference between the two?  (I know one derives from the other)

A related question is: what's the difference between Element and FamilyInstance?  I can't understand why stairs are of class Stairs (derived from Element), while doors are of class FamilyInstance.  Are stairs not an "instance" of a particular "family"?

[jeremytammik · Accepted solution]

Families come in several flavours.

The two main ones are standard and built-in.

Standard are defined in RFA family definitions.

Built-in are built into Revit directly.

Standard families define family symbols, and when you place a family symbol, it is represented by a family instance.

Other elements placed in the model are not called family instances; they are just elements.

Element is a super-class of FamilyInstance.

Analogously, ElementType is a superclass of FamilySymbol.

I hope this explains.

For more info, check the developer guide:

http://help.autodesk.com/view/RVT/2019/ENU/?guid=Revit_API_Revit_API_Developers_Guide_Introduction_E...

Revit Developer's Guide

• Revit API Developers Guide
  • Introduction
    • Getting Started
    • Add-In Integration
    • Application and Document
    • Elements Essentials
      • Element Classification
      • Other Classifications

Cheers,

Jeremy

[garrett]

Ah, that's very helpful, thank you for the explanation and links!

[jeremytammik]

Thank you for your appreciation!

Shared for posterity by The Building Coder:

https://thebuildingcoder.typepad.com/blog/2018/12/dynamo-symbol-vs-type-and-exporter-exception.html#...

Cheers,

Jeremy

[hrasmussen]

Jeremy,
If I had to guess, I'd say you've been the guy with the answer to about 80% of my Revit API questions - thanks for all your posts (this one included)!