Easily Find Polymorphically Associated Records whose destroy callbacks were not called

finding-deleted-associated-records-by-inverse-using-where-not.rb

# The main issue here is, if you do a bunch of delete calls on a model that has associations there will be some other records that
# still exist and point to legit looking values that don't work, because even though the foreign_key exists in the table,
# the record it is pointing to does not.

# For e.g. A User and an Event

# == Schema Information
#
# Table name: users
#
#  id                     :integer          not null, primary key
#  email                  :string(255)      default(""), not null
#

class User < ActiveRecord::Base
  has_many :events, dependent: :destroy
end

# == Schema Information
#
# Table name: events
#
#  id             :integer          not null, primary key
#  user_id        :integer
#  action         :string(255)
#  eventable_id   :integer
#  eventable_type :string(255)
#  created_at     :datetime
#  updated_at     :datetime
#

class Event < ActiveRecord::Base
  belongs_to :user
  belongs_to :eventable, polymorphic: true
end

# If you do `user.delete`, the associated events with that user won't get removed. They will just be hanging there.

# Since you don't have a list of all the IDs that you deleted, the way to approach this is simply get the inverse (or the 'not') 
# of the IDs that do exist.

[11] pry(main)> node_ids = Node.all.map(&:id)
  Node Load (1.0ms)  SELECT "nodes".* FROM "nodes"
=> [38, 43, 39, 44, 34, 35, 36]

[12] pry(main)> Event.where(eventable: node_ids)
  Event Load (0.6ms)  SELECT "events".* FROM "events"  WHERE "events"."eventable_id" IN (38, 43, 39, 44, 34, 35, 36)

=> [#<Event id: 390, user_id: 1, action: "uploaded", eventable_id: 34, eventable_type: "Node", created_at: "2015-12-19 05:57:46", updated_at: "2015-12-19 05:57:46">,
 #<Event id: 391, user_id: 1, action: "uploaded", eventable_id: 35, eventable_type: "Node", created_at: "2015-12-19 06:12:48", updated_at: "2015-12-19 06:12:48">,
 #<Event id: 392, user_id: 1, action: "uploaded", eventable_id: 36, eventable_type: "Node", created_at: "2015-12-19 06:18:40", updated_at: "2015-12-19 06:18:40">,
 #<Event id: 394, user_id: 3, action: "uploaded", eventable_id: 38, eventable_type: "Node", created_at: "2015-12-22 08:53:33", updated_at: "2015-12-22 08:53:33">,
 #<Event id: 395, user_id: 3, action: "uploaded", eventable_id: 39, eventable_type: "Node", created_at: "2015-12-22 09:50:36", updated_at: "2015-12-22 09:50:36">,
 #<Event id: 399, user_id: 3, action: "uploaded", eventable_id: 43, eventable_type: "Node", created_at: "2015-12-22 11:32:52", updated_at: "2015-12-22 11:32:52">,
 #<Event id: 400, user_id: 3, action: "favorited", eventable_id: 43, eventable_type: "Node", created_at: "2015-12-22 11:35:41", updated_at: "2015-12-22 11:35:41">,
 #<Event id: 401, user_id: 3, action: "uploaded", eventable_id: 44, eventable_type: "Node", created_at: "2015-12-22 11:39:01", updated_at: "2015-12-22 11:39:01">]

[13] pry(main)> Event.where.not(eventable: node_ids)
  Event Load (1.1ms)  SELECT "events".* FROM "events"  WHERE ("events"."eventable_id" NOT IN (38, 43, 39, 44, 34, 35, 36))

=> [#<Event id: 387, user_id: 1, action: "uploaded", eventable_id: 31, eventable_type: "Node", created_at: "2015-12-19 05:22:24", updated_at: "2015-12-19 05:22:24">,
 #<Event id: 393, user_id: 3, action: "uploaded", eventable_id: 37, eventable_type: "Node", created_at: "2015-12-22 08:43:44", updated_at: "2015-12-22 08:43:44">,
 #<Event id: 396, user_id: 3, action: "uploaded", eventable_id: 40, eventable_type: "Node", created_at: "2015-12-22 10:28:52", updated_at: "2015-12-22 10:28:52">,
 #<Event id: 397, user_id: 3, action: "uploaded", eventable_id: 41, eventable_type: "Node", created_at: "2015-12-22 10:47:18", updated_at: "2015-12-22 10:47:18">,
 #<Event id: 398, user_id: 3, action: "uploaded", eventable_id: 42, eventable_type: "Node", created_at: "2015-12-22 11:07:06", updated_at: "2015-12-22 11:07:06">]

[14] pry(main)> Event.where.not(eventable: node_ids).destroy_all
  Event Load (0.7ms)  SELECT "events".* FROM "events"  WHERE ("events"."eventable_id" NOT IN (38, 43, 39, 44, 34, 35, 36))
   (1.7ms)  BEGIN
  SQL (3.2ms)  DELETE FROM "events" WHERE "events"."id" = $1  [["id", 387]]
   (3.2ms)  COMMIT
   (0.1ms)  BEGIN
  SQL (0.3ms)  DELETE FROM "events" WHERE "events"."id" = $1  [["id", 393]]
   (0.3ms)  COMMIT
   (0.1ms)  BEGIN
  SQL (0.3ms)  DELETE FROM "events" WHERE "events"."id" = $1  [["id", 396]]
   (0.5ms)  COMMIT
   (0.1ms)  BEGIN
  SQL (0.2ms)  DELETE FROM "events" WHERE "events"."id" = $1  [["id", 397]]
   (0.5ms)  COMMIT
   (0.1ms)  BEGIN
  SQL (0.3ms)  DELETE FROM "events" WHERE "events"."id" = $1  [["id", 398]]
   (0.2ms)  COMMIT

=> [#<Event id: 387, user_id: 1, action: "uploaded", eventable_id: 31, eventable_type: "Node", created_at: "2015-12-19 05:22:24", updated_at: "2015-12-19 05:22:24">,
 #<Event id: 393, user_id: 3, action: "uploaded", eventable_id: 37, eventable_type: "Node", created_at: "2015-12-22 08:43:44", updated_at: "2015-12-22 08:43:44">,
 #<Event id: 396, user_id: 3, action: "uploaded", eventable_id: 40, eventable_type: "Node", created_at: "2015-12-22 10:28:52", updated_at: "2015-12-22 10:28:52">,
 #<Event id: 397, user_id: 3, action: "uploaded", eventable_id: 41, eventable_type: "Node", created_at: "2015-12-22 10:47:18", updated_at: "2015-12-22 10:47:18">,
 #<Event id: 398, user_id: 3, action: "uploaded", eventable_id: 42, eventable_type: "Node", created_at: "2015-12-22 11:07:06", updated_at: "2015-12-22 11:07:06">]