gem 'activerecord-pg_array'

class CreateWolfTracker < ActiveRecord::Migration
  def change
    create_table :wolf_trackers do |t|
      t.string :name
      t.integer :wolf_ids, array: true, default: []
      t.string :pack_names, array: true, default: []
    end

    add_index :wolf_trackers, :wolf_ids, using: 'gin'
  end
end

class WolfTracker < ActiveRecord::Base
  include ActiveRecord::PGArray
  # if doing anything with the pack_names and passing Wold instances, Wolf#name
  # will be the attribute used when serializing to pack_names
  # Using config_array_serializer is optional.
  config_array_serializer pack_names: {:Wolf => :name}
end

tracker.add_wolf(wolfy)            # ActiveRecord object wolfy's id is appended to wolf_ids
tracker.add_wolf!(son_of_wolfy)    # wolf_ids appended with atomic update
tracker.add_wolves([wolfia, 4])    # add multiple to wolf_ids. Note: irregular plural method name and mixed input
tracker.add_wolves!([wolfia, 4])    # add multiple to wolf_ids and persists. Note: irregular plural method name and mixed input. Can take multiple arguments or an array.
tracker.add_wolves!(wolfia, son_of_wolfy) # add multiple and persist. Can take multiple arguments or an array
tracker.remove_wolf(wolfia)        # wolf_ids is modified but not saved
tracker.remove_wolf!(3)            # wolf_ids atomic removal
tracker.remove_wolves(3, wolfia)   # wolf_ids has two items removed but is not persisted. Can take multiple arguments or an array
tracker.remove_wolves!([3, wolfia])  # wolf_ids has two items removed and is persisted. Can take multiple arguments or an array
tracker.wolves                     # looks up wolf objects with ids wolf_ids

tracker.add_pack_name('Stark')
tracker.add_pack_name!('Karstark')
tracker.add_pack_names(['Greyjoy', 'Bolton'])
tracker.remove_pack_name('Greyjoy')
tracker.remove_pack_name!('Bolton')
# Does not define a finder method based on pack_names.
# If you define a custom array_serializer with config_array_serializer you can use this the same like:
tracker.add_pack_names([wolf])
tracker.remove_pack_name!(wolf)