Trying to Combine the Length Parameters of a Beam and an Object.

[Kalvin]

I'm creating a schedule for floor beams & joists in Archicad 27. I'm trying to sneak instances of a Warren Truss 27 object into my schedule, and most things have worked well except the length Parameters. 

Beams contain the following length Parameters: "3D Length", "Length Right", and "Length Left". 

The truss object length parameter is: "Length (A)" 

I want to combine the length parameters into a single column if possible. I thought this would be as simple as creating the following property (expression):

IF ( 3D Length > 0 in, 3D Length, Length (A) )

In layman's terms: If 3D Length is greater than 0 inches, return the 3D Length. If not, return the "Length (A)" value instead. 

I have tried many variations and workarounds besides this, including just 3D Length + Length (A), but every attempt has returned "---", with the evaluation that "Expression cannot be evaluated for this element." I understand why this is happening, but does anyone know of a workaround? I tried ISUNDEFINED, it didn't work. I am now trying to see if I can add one of the parameters to the other, but I don't yet understand how to do that. 

Any help would be appreciated. 

[Toper Barrientos · Accepted solution]

Hi Kalvin.

Try successive expressions (something similar to long  IFs ),
e.g . as shown above.

[Kalvin]

Holy guacamole, thank you man.

Now I feel a little dumb, I did not realize that was possible. Hopefully this helps someone else one day!

Thanks again! 

[Toper Barrientos]

🙂 .. still many hidden mystiques in expression-based properties, esp. when combined with GDL in the future.. 

Cheers !