you cannot define derived attributes on N-N relationships.
In order to solve your problem, follow these steps for each relationship:
- Delete the N-N relationship from your Domain Model
- Add the bridge entity in your Domain model and map it manually on the corresponding bridge table in your database (both bridge tables already exist in your DB)
- Set the two foreign key columns as the primary key of the entity
- Draw two 1-N relationships connecting the new entity with the ones connected through the old N-N relationship. The 1 cardinality is referred to the role of the relationship having the new entity as target.
- Map manually the two 1-N relationships using the existing column of the new entity as the foreign key and its oid column as oid of the other entity.
- Launch the warning on the Domain Model to be sure that there are not mistakes.
If you want to learn more about this topic please refer to the following online lesson: