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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)
record.save! if record.new_record?
end
end
super
end
def concat_records(records)
ensure_not_nested
records = super
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
count = scope.destroy_all.length
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]
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
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