Want to populate the workorder location field when location is null

1. Frist priority is to populate it by selecting value from domain as per site default location value. Also need to check that default location should be active or operative.

2. 2nd priority., to populate by the primarysystem location of site from location hierarchy table.

Could you help me how can i do that..

I don't have a direct answer for you, but what database are you using? Can you generate a single value that you want using a query? I know in some of my reports, I use the NVL function in Oracle, to query values if field data is null.

https://www.oracletutorial.com/oracle-comparison-functions/oracle-nvl/

also for sql server, I think you can use isnull, case, or coalesce:

http://www.sqlines.com/oracle/functions/nvl

Once you have the value, I'm thinking an automation script to perform those queries and bring the value you need when workorder.location is null could work?