Q:

How to delete Active Record object with a foreign key without using cascading deletes?

I have two models, LaserSheet and Item, that relate to each other with a has_many relationship:
class LaserSheet < ActiveRecord::Base
  belongs_to :job
  has_many :items
  ...
end

class Item < ActiveRecord::Base
  belongs_to :job
  has_many :laser_sheets
  ...
end

Because they have a many-to-many relationship, I want to be able to delete an Item without deleting its associated LaserSheets, and similarly delete a LaserSheet without deleting its associated Items. However, when I attempt to delete one of the objects I get a Foreign Key error:
ERROR: update or delete on table "items" violates foreign key constraint "fk_rails_f7f551ebf9" on table "laser_sheets" DETAIL: Key (id)=(293) is still referenced from table "laser_sheets".

EDIT:
DB migrations adding refs between the two models:
class AddItemRefToLaserSheets < ActiveRecord::Migration
  def change
    add_reference :laser_sheets, :item
  end
end

class AddLaserSheetRefToItems < ActiveRecord::Migration
  def change
    add_reference :items, :laser_sheet
  end
end

A:

Check out the dependent options.  You may want something like:
class LaserSheet < ActiveRecord::Base
  has_many :items, dependent: :nullify
  ...

class Item < ActiveRecord::Base
  has_many :laser_sheets, dependent: :nullify
  ...

