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_on_replace(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: update_counters(-1) end def increment_counters # :nodoc: update_counters(1) end private def update_counters(by) if require_counter_update? && foreign_key_present? if target && !stale_target? target.increment!(reflection.counter_cache_column, by) else klass.update_counters(target_id, reflection.counter_cache_column => by) end end end def find_target? !loaded? && foreign_key_present? && klass end def require_counter_update? reflection.counter_cache_column && owner.persisted? end def update_counters_on_replace(record) if require_counter_update? && different_target?(record) record.increment!(reflection.counter_cache_column) decrement_counters 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) { |n| owner.send(:missing_attribute, n, caller) } result && result.to_s end end end end