Say I have these tables which define hierarchy

Org

• id
• name

SubOrg

• id
• org_id
• name

Now there is another table which refers both such that:

Rules

• id
• org_id
• sub_org_id (nullable)
• …

The way Rules table works is if sub_org_id is null, the rule applies to whole org. if sub_ord_id is not null, that rule overrides for that particular sub_org.

How do I map this into sqlalchemy relationship?

Thanks