From 524238139025ccddfa886bcfd7a1a6434954e305 Mon Sep 17 00:00:00 2001 From: Yasyf Mohamedali Date: Mon, 2 Mar 2015 17:18:35 -0500 Subject: [PATCH] Honour the order of the joining model in a `has_many :through` association when eager loading. Previously, eager loading a `has_many :through` association with no defined order would return the records in the natural order of the database. Now, these records will be returned in the order that the joining record is returned, in case there is a defined order there. --- activerecord/CHANGELOG.md | 15 +++++++++ .../associations/preloader/association.rb | 2 +- .../preloader/through_association.rb | 23 ++++++++----- .../test/cases/associations/eager_test.rb | 32 +++++++++++++++++++ activerecord/test/models/tag.rb | 6 ++++ 5 files changed, 69 insertions(+), 9 deletions(-) diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index b5dd19988d..e63f86d45e 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,18 @@ +* Honour the order of the joining model in a `has_many :through` association when eager loading. + + Example: + + The below will now follow the order of `by_lines` when eager loading `authors`. + + class Article < ActiveRecord::Base + has_many :by_lines, -> { order(:position) } + has_many :authors, through: :by_lines + end + + Fixes #17864. + + *Yasyf Mohamedali*, *Joel Turkel* + * Dont enroll records in the transaction if they dont have commit callbacks. That was causing a memory grow problem when creating a lot of records inside a transaction. diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb index 1dc8bff193..91de52e7e7 100644 --- a/activerecord/lib/active_record/associations/preloader/association.rb +++ b/activerecord/lib/active_record/associations/preloader/association.rb @@ -86,7 +86,7 @@ module ActiveRecord if owner_keys.any? # 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 - sliced = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size) + sliced = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size) records = load_slices sliced records.each do |record, owner_key| diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb index 56aa23b173..5adb0aac65 100644 --- a/activerecord/lib/active_record/associations/preloader/through_association.rb +++ b/activerecord/lib/active_record/associations/preloader/through_association.rb @@ -37,12 +37,7 @@ module ActiveRecord } end - record_offset = {} - @preloaded_records.each_with_index do |record,i| - record_offset[record] = i - end - - through_records.each_with_object({}) { |(lhs,center),records_by_owner| + through_records.each_with_object({}) do |(lhs,center), records_by_owner| pl_to_middle = center.group_by { |record| middle_to_pl[record] } records_by_owner[lhs] = pl_to_middle.flat_map do |pl, middles| @@ -52,13 +47,25 @@ module ActiveRecord association.reader }.compact - rhs_records.sort_by { |rhs| record_offset[rhs] } + # Respect the order on `reflection_scope` if it exists, else use the natural order. + if reflection_scope.values[:order].present? + @id_map ||= id_to_index_map @preloaded_records + rhs_records.sort_by { |rhs| @id_map[rhs] } + else + rhs_records + end end - } + end end private + def id_to_index_map(ids) + id_map = {} + ids.each_with_index { |id, index| id_map[id] = index } + id_map + end + def reset_association(owners, association_name) should_reset = (through_scope != through_reflection.klass.unscoped) || (reflection.options[:source_type] && through_reflection.collection?) diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb index 7d8b933992..79e660c7e5 100644 --- a/activerecord/test/cases/associations/eager_test.rb +++ b/activerecord/test/cases/associations/eager_test.rb @@ -743,6 +743,38 @@ class EagerAssociationTest < ActiveRecord::TestCase } end + def test_eager_has_many_through_with_order + tag = OrderedTag.create(name: 'Foo') + post1 = Post.create!(title: 'Beaches', body: "I like beaches!") + post2 = Post.create!(title: 'Pools', body: "I like pools!") + + Tagging.create!(taggable_type: 'Post', taggable_id: post1.id, tag: tag) + Tagging.create!(taggable_type: 'Post', taggable_id: post2.id, tag: tag) + + tag_with_includes = OrderedTag.includes(:tagged_posts).find(tag.id) + assert_equal(tag_with_includes.taggings.map(&:taggable).map(&:title), tag_with_includes.tagged_posts.map(&:title)) + end + + def test_eager_has_many_through_multiple_with_order + tag1 = OrderedTag.create!(name: 'Bar') + tag2 = OrderedTag.create!(name: 'Foo') + + post1 = Post.create!(title: 'Beaches', body: "I like beaches!") + post2 = Post.create!(title: 'Pools', body: "I like pools!") + + Tagging.create!(taggable: post1, tag: tag1) + Tagging.create!(taggable: post2, tag: tag1) + Tagging.create!(taggable: post2, tag: tag2) + Tagging.create!(taggable: post1, tag: tag2) + + tags_with_includes = OrderedTag.where(id: [tag1, tag2].map(&:id)).includes(:tagged_posts).order(:id).to_a + tag1_with_includes = tags_with_includes.first + tag2_with_includes = tags_with_includes.last + + assert_equal([post2, post1].map(&:title), tag1_with_includes.tagged_posts.map(&:title)) + assert_equal([post1, post2].map(&:title), tag2_with_includes.tagged_posts.map(&:title)) + end + def test_eager_with_default_scope developer = EagerDeveloperWithDefaultScope.where(:name => 'David').first projects = Project.order(:id).to_a diff --git a/activerecord/test/models/tag.rb b/activerecord/test/models/tag.rb index 80d4725f7e..b48b9a2155 100644 --- a/activerecord/test/models/tag.rb +++ b/activerecord/test/models/tag.rb @@ -5,3 +5,9 @@ class Tag < ActiveRecord::Base has_many :tagged_posts, :through => :taggings, :source => 'taggable', :source_type => 'Post' end + +class OrderedTag < Tag + self.table_name = "tags" + + has_many :taggings, -> { order('taggings.id DESC') }, foreign_key: 'tag_id' +end