Calculation attribute rule using fields from different feature classes

SuzyFer

I need to create a calculation attribute rule that takes values from two different feature classes.
For example, there are two feature classes: "woodland" and "openSpace". These two feature classes have a common column "id" that I can join them by. Both of these feature classes also have "area" field (with an immediate calculation rule for this already set up) - calculating the area within each id.

I have a field "totalArea" in "woodland" feature class, and I need to sum the area fields from both "woodland" and "openSpace" into the "totalArea" with an Arcade expression - so every time the geometry is updated in either of these feature classes, I do not need to calculate fields to get updated areas - including for "totalArea".

I am fairly new to Arcade but expecting that this is going to be a simple expression to set up. I cannot seem to find an answer on how to achieve this. 

Thank you.

DavidSolari

The FeatureSetByName function is your friend for getting data from other feature classes. As for updating another feature class from your rule, this help page explains the structure of the special object you have to return.