get_change(changeset, :field) is basically the same as changeset |> apply_changes() |> Map.get(:field), so I’m not really sure what you’re missing for it. Also Ecto.Changeset does validate just the changes, as the idea is that a given source struct is already valid and only the params need to be validated, but you can just as well validate any given change against it’s consequences for the validity of the whole struct.
