Hey all! I’m implementing something similar to the polymorphic todo list in Plataformatec’s What’s new in Ecto 2.1 (I’ll be using the todo list example in this post). It works fine, however getting deletion in a one-to-many relationship (since any TodoItem will only be on one TodoList or Project) using a join table is a bit tricky. I’ve set the on_delete option on the references in the todo_list_items and the projects_items tables to :delete_all, which works fine for deleting the join table record when a TodoItem, a TodoList, or a Project is deleted. As expected though, when a TodoList or a Project is deleted, the TodoItems associated with it aren’t deleted, which would be desirable in my domain since, using the todo list as an example, moving a TodoItem to a different Project or TodoList wouldn’t make sense. I’ve found in the Ecto docs where this is how :delete_all behaves (which makes sense for the majority of many_to_many uses), but I was wondering if there is a setting in Ecto that would delete the TodoItems when a Project or TodoList is deleted? Or will I have to do this myself either in an Ecto.Multi or with a PostgreSQL trigger?
