blrobin2 · January 6, 2021 15:16
diff --git a/autosave_associated_many_to_many.rb b/autosave_associated_many_to_many.rb
 module AutosaveAssociatedManyToMany
  extend ActiveSupport::Concern

  # When using a combination of autosave and accepts nested_attributes_for for a many-to-many association
  # By default, Rails always creates new records
  # If you have unique indexes on the association keys on your bridge table, you'll just get errors
  # By defining a matcher, you provide a way to determine whether a "new" record is actually an existing record
  # By defining an updater, you provide a way to update values on a many-to-many (changing an association to a new field
  # or updating any additional fields on the bridge table)
  #
  # Best utilized by calling within autosave_associated_records_for_{association}, an autosave hook that Rails
  # implements, where {association} is the same name as the association you wish to handle autosave
  def handle_many_to_many_autosave(association, matcher, updater = ->(_record, _record_update) {})
    raise NotImplementedError "association #{association} not defined for #{self.name}" unless self.respond_to?(association)
    unless matcher.respond_to?(:call) && matcher.arity == 2
      raise ArgumentError "matcher must respond to :call and accept old and new record arguments"
    end
    unless updater.respond_to?(:call) && updater.arity == 2
      raise ArgumentError "updater must respond to :call and accept old and update record arguments"
    end

    records = self.send(association)
    existing = records.reject { |record| record.id.nil? }
    incoming = records.select { |record| record.id.nil? }

    # Remove ones that are in existing but not new
    existing.select { |record| incoming.none? { |new_record| matcher.call(record, new_record) } }.map(&:destroy)
    # Add ones that are in new but not existing
    to_add = incoming.select { |new_record| existing.none? { |record| matcher.call(record, new_record) } }
    # Update ones that are in both and if the count has been updated
    existing.each do |record|
      update = incoming.find { |new_record| matcher.call(record, new_record) }
      next unless update
      updater.call(record, update)
      record.save!
    end

    self.send(association) << to_add
  end
 end
	module AutosaveAssociatedManyToMany
	extend ActiveSupport::Concern

	# When using a combination of autosave and accepts nested_attributes_for for a many-to-many association
	# By default, Rails always creates new records
	# If you have unique indexes on the association keys on your bridge table, you'll just get errors
	# By defining a matcher, you provide a way to determine whether a "new" record is actually an existing record
	# By defining an updater, you provide a way to update values on a many-to-many (changing an association to a new field
	# or updating any additional fields on the bridge table)
	#
	# Best utilized by calling within autosave_associated_records_for_{association}, an autosave hook that Rails
	# implements, where {association} is the same name as the association you wish to handle autosave
	def handle_many_to_many_autosave(association, matcher, updater = ->(_record, _record_update) {})
	raise NotImplementedError "association #{association} not defined for #{self.name}" unless self.respond_to?(association)
	unless matcher.respond_to?(:call) && matcher.arity == 2
	raise ArgumentError "matcher must respond to :call and accept old and new record arguments"
	end
	unless updater.respond_to?(:call) && updater.arity == 2
	raise ArgumentError "updater must respond to :call and accept old and update record arguments"
	end

	records = self.send(association)
	existing = records.reject { \|record\| record.id.nil? }
	incoming = records.select { \|record\| record.id.nil? }

	# Remove ones that are in existing but not new
	existing.select { \|record\| incoming.none? { \|new_record\| matcher.call(record, new_record) } }.map(&:destroy)
	# Add ones that are in new but not existing
	to_add = incoming.select { \|new_record\| existing.none? { \|record\| matcher.call(record, new_record) } }
	# Update ones that are in both and if the count has been updated
	existing.each do \|record\|
	update = incoming.find { \|new_record\| matcher.call(record, new_record) }
	next unless update
	updater.call(record, update)
	record.save!
	end

	self.send(association) << to_add
	end
	end