module ActiveRecord # = Active Record Belongs To Association module Associations class BelongsToAssociation < SingularAssociation #:nodoc: def handle_dependency target.send(options[:dependent]) if load_target end def replace(record) if record raise_on_type_mismatch!(record) update_counters(record) replace_keys(record) set_inverse_instance(record) @updated = true else decrement_counters remove_keys end self.target = record end def reset super @updated = false end def updated? @updated end def decrement_counters # :nodoc: with_cache_name { |name| decrement_counter name } end def increment_counters # :nodoc: with_cache_name { |name| increment_counter name } end private def find_target? !loaded? && foreign_key_present? && klass end def with_cache_name counter_cache_name = reflection.counter_cache_column return unless counter_cache_name && owner.persisted? yield counter_cache_name end def update_counters(record) with_cache_name do |name| return unless different_target? record record.class.increment_counter(name, record.id) decrement_counter name end end def decrement_counter(counter_cache_name) if foreign_key_present? klass.decrement_counter(counter_cache_name, target_id) end end def increment_counter(counter_cache_name) if foreign_key_present? klass.increment_counter(counter_cache_name, target_id) if target && !stale_target? target.increment(counter_cache_name) end end end # Checks whether record is different to the current target, without loading it def different_target?(record) record.id != owner._read_attribute(reflection.foreign_key) end def replace_keys(record) owner[reflection.foreign_key] = record._read_attribute(reflection.association_primary_key(record.class)) end def remove_keys owner[reflection.foreign_key] = nil end def foreign_key_present? owner._read_attribute(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.has_one? end def target_id if options[:primary_key] owner.send(reflection.name).try(:id) else owner._read_attribute(reflection.foreign_key) end end def stale_state result = owner._read_attribute(reflection.foreign_key) result && result.to_s end end end end