module ActiveRecord # = Active Record Has Many Through Association module Associations class HasManyThroughAssociation < HasManyAssociation #:nodoc: include ThroughAssociation def initialize(owner, reflection) super @through_records = {} @through_association = nil end # Returns the size of the collection by executing a SELECT COUNT(*) query if the collection hasn't been # loaded and calling collection.size if it has. If it's more likely than not that the collection does # have a size larger than zero, and you need to fetch that collection afterwards, it'll take one fewer # SELECT query if you use #length. def size if has_cached_counter? owner.send(:read_attribute, cached_counter_attribute_name) elsif loaded? target.size else count end end def concat(*records) unless owner.new_record? records.flatten.each do |record| raise_on_type_mismatch!(record) end end super end def concat_records(records) ensure_not_nested records = super(records, true) if owner.new_record? && records records.flatten.each do |record| build_through_record(record) end end records end def insert_record(record, validate = true, raise = false) ensure_not_nested if record.new_record? if raise record.save!(:validate => validate) else return unless record.save(:validate => validate) end end save_through_record(record) update_counter(1) record end private def through_association @through_association ||= owner.association(through_reflection.name) end # We temporarily cache through record that has been build, because if we build a # through record in build_record and then subsequently call insert_record, then we # want to use the exact same object. # # However, after insert_record has been called, we clear the cache entry because # we want it to be possible to have multiple instances of the same record in an # association def build_through_record(record) @through_records[record.object_id] ||= begin ensure_mutable through_record = through_association.build through_record.send("#{source_reflection.name}=", record) through_record end end def save_through_record(record) build_through_record(record).save! ensure @through_records.delete(record.object_id) end def build_record(attributes) ensure_not_nested record = super(attributes) inverse = source_reflection.inverse_of if inverse if inverse.macro == :has_many record.send(inverse.name) << build_through_record(record) elsif inverse.macro == :has_one record.send("#{inverse.name}=", build_through_record(record)) end end record end def target_reflection_has_associated_record? !(through_reflection.macro == :belongs_to && owner[through_reflection.foreign_key].blank?) end def update_through_counter?(method) case method when :destroy !inverse_updates_counter_cache?(through_reflection) when :nullify false else true end end def delete_records(records, method) ensure_not_nested # This is unoptimised; it will load all the target records # even when we just want to delete everything. records = load_target if records == :all scope = through_association.scope scope.where! construct_join_attributes(*records) case method when :destroy if scope.klass.primary_key count = scope.destroy_all.length else scope.to_a.each do |record| record.run_callbacks :destroy end arel = scope.arel stmt = Arel::DeleteManager.new arel.engine stmt.from scope.klass.arel_table stmt.wheres = arel.constraints count = scope.klass.connection.delete(stmt, 'SQL', scope.bind_values) end when :nullify count = scope.update_all(source_reflection.foreign_key => nil) else count = scope.delete_all end delete_through_records(records) if source_reflection.options[:counter_cache] && method != :destroy counter = source_reflection.counter_cache_column klass.decrement_counter counter, records.map(&:id) end if through_reflection.macro == :has_many && update_through_counter?(method) update_counter(-count, through_reflection) end update_counter(-count) end def through_records_for(record) attributes = construct_join_attributes(record) candidates = Array.wrap(through_association.target) candidates.find_all { |c| c.attributes.slice(*attributes.keys) == attributes } end def delete_through_records(records) records.each do |record| through_records = through_records_for(record) if through_reflection.macro == :has_many through_records.each { |r| through_association.target.delete(r) } else if through_records.include?(through_association.target) through_association.target = nil end end @through_records.delete(record.object_id) end end def find_target return [] unless target_reflection_has_associated_record? scope.to_a end # NOTE - not sure that we can actually cope with inverses here def invertible_for?(record) false end end end end