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| author | Ryuta Kamizono <kamipo@gmail.com> | 2019-03-28 04:42:38 +0900 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2019-03-28 04:42:38 +0900 |
| commit | 3a0929901ffa852bab9644c662b811d42780c3a1 (patch) | |
| tree | fe0a02591c61c8ebcdcfd19265f1289537089ad6 | |
| parent | 0223665c971b98fe0ac82b78b485ee1330d4c1e3 (diff) | |
| parent | 2847653869ffc1ff5139c46e520c72e26618c199 (diff) | |
| download | rails-3a0929901ffa852bab9644c662b811d42780c3a1.tar.gz rails-3a0929901ffa852bab9644c662b811d42780c3a1.tar.bz2 rails-3a0929901ffa852bab9644c662b811d42780c3a1.zip | |
Merge pull request #35496 from bogdan/right-preloading
Fix preloader to never reset associations in case they are already loaded
4 files changed, 99 insertions, 64 deletions
diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb index 8997579527..c7cd87f9d4 100644 --- a/activerecord/lib/active_record/associations/preloader.rb +++ b/activerecord/lib/active_record/associations/preloader.rb @@ -143,9 +143,7 @@ module ActiveRecord def preloaders_for_reflection(reflection, records, scope) records.group_by { |record| record.association(reflection.name).klass }.map do |rhs_klass, rs| - loader = preloader_for(reflection, rs).new(rhs_klass, rs, reflection, scope) - loader.run self - loader + preloader_for(reflection, rs).new(rhs_klass, rs, reflection, scope).run end end @@ -166,10 +164,18 @@ module ActiveRecord @reflection = reflection end - def run(preloader); end + def run + self + end def preloaded_records - owners.flat_map { |owner| owner.association(reflection.name).target } + @preloaded_records ||= records_by_owner.flat_map(&:last) + end + + def records_by_owner + @records_by_owner ||= owners.each_with_object({}) do |owner, result| + result[owner] = Array(owner.association(reflection.name).target) + end end private diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb index 7048ff43b8..46532f651e 100644 --- a/activerecord/lib/active_record/associations/preloader/association.rb +++ b/activerecord/lib/active_record/associations/preloader/association.rb @@ -4,26 +4,44 @@ module ActiveRecord module Associations class Preloader class Association #:nodoc: - attr_reader :preloaded_records - def initialize(klass, owners, reflection, preload_scope) @klass = klass @owners = owners @reflection = reflection @preload_scope = preload_scope @model = owners.first && owners.first.class - @preloaded_records = [] end - def run(preloader) - records = load_records do |record| - owner = owners_by_key[convert_key(record[association_key_name])] - association = owner.association(reflection.name) - association.set_inverse_instance(record) + def run + if !preload_scope || preload_scope.empty_scope? + owners.each do |owner| + associate_records_to_owner(owner, records_by_owner[owner] || []) + end + else + # Custom preload scope is used and + # the association can not be marked as loaded + # Loading into a Hash instead + records_by_owner end + self + end - owners.each do |owner| - associate_records_to_owner(owner, records[convert_key(owner[owner_key_name])] || []) + def records_by_owner + @records_by_owner ||= preloaded_records.each_with_object({}) do |record, result| + owners_by_key[convert_key(record[association_key_name])].each do |owner| + (result[owner] ||= []) << record + end + end + end + + def preloaded_records + return @preloaded_records if defined?(@preloaded_records) + return [] if owner_keys.empty? + # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000) + # Make several smaller queries if necessary or make one query if the adapter supports it + slices = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size) + @preloaded_records = slices.flat_map do |slice| + records_for(slice) end end @@ -54,13 +72,10 @@ module ActiveRecord end def owners_by_key - unless defined?(@owners_by_key) - @owners_by_key = owners.each_with_object({}) do |owner, h| - key = convert_key(owner[owner_key_name]) - h[key] = owner if key - end + @owners_by_key ||= owners.each_with_object({}) do |owner, result| + key = convert_key(owner[owner_key_name]) + (result[key] ||= []) << owner if key end - @owners_by_key end def key_conversion_required? @@ -87,23 +102,16 @@ module ActiveRecord @model.type_for_attribute(owner_key_name).type end - def load_records(&block) - return {} if owner_keys.empty? - # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000) - # Make several smaller queries if necessary or make one query if the adapter supports it - slices = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size) - @preloaded_records = slices.flat_map do |slice| - records_for(slice, &block) - end - @preloaded_records.group_by do |record| - convert_key(record[association_key_name]) + def records_for(ids) + scope.where(association_key_name => ids).load do |record| + # Processing only the first owner + # because the record is modified but not an owner + owner = owners_by_key[convert_key(record[association_key_name])].first + association = owner.association(reflection.name) + association.set_inverse_instance(record) end end - def records_for(ids, &block) - scope.where(association_key_name => ids).load(&block) - end - def scope @scope ||= build_scope end diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb index db89b77629..bec1c4c94a 100644 --- a/activerecord/lib/active_record/associations/preloader/through_association.rb +++ b/activerecord/lib/active_record/associations/preloader/through_association.rb @@ -4,45 +4,57 @@ module ActiveRecord module Associations class Preloader class ThroughAssociation < Association # :nodoc: - def run(preloader) - already_loaded = owners.first.association(through_reflection.name).loaded? - through_scope = through_scope() - through_preloaders = preloader.preload(owners, through_reflection.name, through_scope) - middle_records = through_preloaders.flat_map(&:preloaded_records) - preloaders = preloader.preload(middle_records, source_reflection.name, scope) - @preloaded_records = preloaders.flat_map(&:preloaded_records) - - owners.each do |owner| - through_records = Array(owner.association(through_reflection.name).target) - - if already_loaded + PRELOADER = ActiveRecord::Associations::Preloader.new + + def initialize(*) + super + @already_loaded = owners.first.association(through_reflection.name).loaded? + end + + def preloaded_records + @preloaded_records ||= source_preloaders.flat_map(&:preloaded_records) + end + + def records_by_owner + return @records_by_owner if defined?(@records_by_owner) + source_records_by_owner = source_preloaders.map(&:records_by_owner).reduce(:merge) + through_records_by_owner = through_preloaders.map(&:records_by_owner).reduce(:merge) + + @records_by_owner = owners.each_with_object({}) do |owner, result| + through_records = through_records_by_owner[owner] || [] + + if @already_loaded if source_type = reflection.options[:source_type] through_records = through_records.select do |record| record[reflection.foreign_type] == source_type end end - else - owner.association(through_reflection.name).reset if through_scope end - result = through_records.flat_map do |record| - record.association(source_reflection.name).target + records = through_records.flat_map do |record| + source_records_by_owner[record] end - result.compact! - result.sort_by! { |rhs| preload_index[rhs] } if scope.order_values.any? - result.uniq! if scope.distinct_value - associate_records_to_owner(owner, result) - end - - unless scope.empty_scope? - middle_records.each do |owner| - owner.association(source_reflection.name).reset if owner - end + records.compact! + records.sort_by! { |rhs| preload_index[rhs] } if scope.order_values.any? + records.uniq! if scope.distinct_value + result[owner] = records end end private + def source_preloaders + @source_preloaders ||= PRELOADER.preload(middle_records, source_reflection.name, scope) + end + + def middle_records + through_preloaders.flat_map(&:preloaded_records) + end + + def through_preloaders + @through_preloaders ||= PRELOADER.preload(owners, through_reflection.name, through_scope) + end + def through_reflection reflection.through_reflection end @@ -52,8 +64,8 @@ module ActiveRecord end def preload_index - @preload_index ||= @preloaded_records.each_with_object({}).with_index do |(id, result), index| - result[id] = index + @preload_index ||= preloaded_records.each_with_object({}).with_index do |(record, result), index| + result[record] = index end end @@ -96,7 +108,7 @@ module ActiveRecord end end - scope unless scope.empty_scope? + scope end end end diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb index 0b83fd8421..35da74102d 100644 --- a/activerecord/test/cases/associations/nested_through_associations_test.rb +++ b/activerecord/test/cases/associations/nested_through_associations_test.rb @@ -548,6 +548,15 @@ class NestedThroughAssociationsTest < ActiveRecord::TestCase end end + def test_through_association_preload_doesnt_reset_source_association_if_already_preloaded + blue = tags(:blue) + authors = Author.preload(posts: :first_blue_tags_2, misc_post_first_blue_tags_2: {}).to_a.sort_by(&:id) + + assert_no_queries do + assert_equal [blue], authors[2].posts.first.first_blue_tags_2 + end + end + def test_nested_has_many_through_with_conditions_on_source_associations_preload_via_joins # Pointless condition to force single-query loading assert_includes_and_joins_equal( |