Managing a many-to-many relationship

    many_to_many :thumbnails, Eravuokraamo.Media.File do
      public? true
      through Eravuokraamo.Media.ProductFile
      destination_attribute_on_join_resource :file_id
      filter expr(product_files.role == :thumbnail)
    end

    update :update do
      primary? true
      accept [:name, :price, :description, :translations]

      argument :category_ids, {:array, :uuid}
      argument :thumbnails, {:array, :map}

      change manage_relationship(:category_ids, :categories, type: :append_and_remove)

      change manage_relationship(:thumbnails,
               type: :append_and_remove,
               join_keys: [:role, :sort_order]
             )

      require_atomic? false
    end