You might also find help in the free and very good "Little Ecto Cookbook". See "Constraints and Upserts" as well as "Polymorphic associations with many to many

You might also find help in the free and very good "Little Ecto Cookbook". See "Constraints and Upserts" as well as "Polymorphic associations with many to many". https://dashbit.co/ebooks/the-little-ecto-cookbook https://dashbit.co/ebooks/the-little-ecto-cookbook