module ActiveRecord # = Active Record Belongs To Associations module Associations class BelongsToAssociation < SingularAssociation #:nodoc: def replace(record) raise_on_type_mismatch(record) if record update_counters(record) replace_keys(record) set_inverse_instance(record) @updated = true if record self.target = record end def updated? @updated end private def find_target? !loaded? && foreign_key_present? && klass end def update_counters(record) counter_cache_name = reflection.counter_cache_column if counter_cache_name && owner.persisted? && different_target?(record) if record record.class.increment_counter(counter_cache_name, record.id) end if foreign_key_present? klass.decrement_counter(counter_cache_name, target_id) end end end # Checks whether record is different to the current target, without loading it def different_target?(record) record.nil? && owner[reflection.foreign_key] || record && record.id != owner[reflection.foreign_key] end def replace_keys(record) if record owner[reflection.foreign_key] = record[reflection.association_primary_key(record.class)] else owner[reflection.foreign_key] = nil end end def foreign_key_present? owner[reflection.foreign_key] end # NOTE - for now, we're only supporting inverse setting from belongs_to back onto # has_one associations. def invertible_for?(record) inverse = inverse_reflection_for(record) inverse && inverse.macro == :has_one end def target_id if options[:primary_key] owner.send(reflection.name).try(:id) else owner[reflection.foreign_key] end end def stale_state owner[reflection.foreign_key] && owner[reflection.foreign_key].to_s end end end end