Property Calculator - Validate Class against Allowed Classes (MSLU)

Hi :) 

I am trying to implement a validation rule using Property Calculator and I am wondering what would be the recommended approach.

My configuration is:

Object type:

• Document

Properties on the document:

• Class (lookup)
• Document Subtype (lookup)

Properties on the Document Subtype object:

• Allowed Classes (multi-select lookup)

Example:

Document Class = Report
Document Subtype = My Subtype

Allowed Classes on the selected subtype:
- Review
- Internal Review

The goal is to block the save when the selected document Class is not included in the Allowed Classes of the selected Document Subtype.

I have tried several approaches using Property Calculator Error Cases without success:

• Direct comparisons (=, <>)
• IN
• LIKE (not ideal because some class names may be similar)
• Temporary MSLU properties
• Filter Lookup Values
• Combining lookup and MSLU values using +
• Subtracting MSLU values using -

I also tested some of these approaches using temporary calculated MSLU properties to separate the calculations from the validation logic.

At this point I am not sure whether I am missing a supported Property Calculator feature or trying to solve the problem the wrong way.

How would you implement this validation using Property Calculator?

Thanks!