Question

Can I use DAX to apply row-level security by matching a substring in the username to a column value?

I'm implementing row-level security in Power BI and want to grant access to rows based on whether the logged-in user’s username contains a specific substring that matches values in a column. I need to know if DAX can handle this kind of partial match for dynamic security rules.

Answer 1

Yes, you can implement row-level security (RLS) in Power BI using DAX with substring matching via the USERNAME() function and SEARCH().

Example DAX RLS Filter Rule

Assume you want to match part of the username to values in the [RegionKey] column:

SEARCH([RegionKey], USERNAME(), 1, 0) > 0

• USERNAME() returns the full UPN (e.g., user@domain.com).

• SEARCH() checks if [RegionKey] appears anywhere in the username.

• > 0 ensures a match; 0 means not found.