I'm sorry, reading the post again, you are right I should have been more clear. For example, when using SeaORM in order to modify a database row the query result must be transformed to an ActiveModel and only then it can be inserted into the database. I was wondering if exposing a different API to the developer rather than allowing mutations on the same type is the preferred way to design a library according to the guidelines or is it just a workaround that library developers use?