What is going on? Occurrence.SurfaceBodies Count is zero for parts with no solid parts

[wfajber]

Dim occ As Inventor.ComponentOccurrence
occ = ThisApplication.CommandManager.Pick(Inventor.SelectionFilterEnum.kAssemblyOccurrenceFilter, "pick an occurrence") 
Logger.Info("For part " & occ.Name & " The number of surface bodies is " & occ.SurfaceBodies.Count)

I was debugging a rule, and I became confused about surfacebodies.   I was adding a part that is nothing but surface.  I was repurposing a rule that got an edge from a occurrence, which worked great.  I switched to a part that does not have any solids, and it failed.

Here are two parts. They are identical except in one of them I extruded the profile as a surface instead of a solid.

When I select the occurrence of the solid part, the number of SurfaceBodies= 1. 

But when I select the occurrence of the surface part, the number of SurfaceBodies= 0.

But I can see it. In the model browser, I can see a surface in the SurfaceBody browser.  

Clearly there is a subtlety around how a how an occurrence displays the surface. Can anyone explain this? 

[vpeuvion]

Hi, this will maybe can help you :

https://forums.autodesk.com/t5/inventor-programming-ilogic/ilogic-access-surface-bodies/td-p/5684956

Vincent.

[Michael.Navara]

I don't know how it is designed, but you can obtain WorkSurfaces from occ.Definition.WorkSurfaces

Dim occ As Inventor.ComponentOccurrence
occ = ThisApplication.CommandManager.Pick(Inventor.SelectionFilterEnum.kAssemblyOccurrenceFilter, "pick an occurrence") 
Logger.Info("For part " & occ.Name & " The number of surface bodies is " & occ.SurfaceBodies.Count)
Logger.Info("For part " & occ.Name & " The number of work surfaces is " & occ.Definition.WorkSurfaces.Count)

Note: Both models are empty ☹️