Similar but separate Feature classes with differing field names | If Then , OR won’t recognize one field

jhomme981

Hi! Im using ArcMap 10.x in ModelBuilder working with Electrical linear segments and calculating attributes: Overhead (OH) Primary lines and Underground (UG) primary lines. OH primary has field name: conductorMaterial, and the UG primary has the equivalent field name titled: neutralMaterial. 
I’m looking to have one statement that captures both fields attributes and use the THEN to = my combinedMaterial field.
i.e., If [conductorMaterial = “aluminum” Or [neutralMaterial] = “aluminum” Then
 combinedMaterial = “ACSR Cables”

Since conductorMaterial only exists in one attribute table and neutralMaterial exists in the other, I get an error because one field doesn’t exist for the expression. I could potentially create a new field and add more steps than I’d like but is there a way for a calculation to run even though a field may not be present?  I really hope that was clear. Thank ya for checking!!

curtvprice

In ArcMap, the precondition route (no "If" tool as we have in Pro ModelBuilder) would be more complicated, so it may make more sense to build your select expression in Python using the Calculate Value tool with logic based on what fields are there, and pass that SQL expression to the select by attributes tool.