From 23c656c1bc113e5f198464ad29d72c5238bfd796 Mon Sep 17 00:00:00 2001 From: Ben Woosley Date: Tue, 14 May 2013 15:01:20 +0200 Subject: Backport a super-simplified version of #6792, fixing that #exists? and others can produce invalid SQL: "SELECT DISTINCT DISTINCT" The combination of a :uniq => true association and the #distinct call in #construct_limited_ids_condition combine to create invalid SQL, because we're explicitly selecting DISTINCT, and also sending #distinct on to AREL, via the relation#distinct_value. Where #6792 was the forever fix, this is the minimal fix. Instead of properly indicating the distinctness of the query through #uniq_value alone, we use a literal select statement and set #uniq_value to always be falsey --- activerecord/CHANGELOG.md | 7 +++++++ activerecord/lib/active_record/relation/finder_methods.rb | 1 + activerecord/test/cases/finder_test.rb | 12 ++++++++++++ 3 files changed, 20 insertions(+) diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index e679d4f781..f8c75c0fba 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,5 +1,12 @@ ## unreleased ## +* Fix that under some conditions, Active Record could produce invalid SQL of the sort: + "SELECT DISTINCT DISTINCT". + + Backport of #6792. + + *Ben Woosley* + * Require `ActiveRecord::Base` in railtie hooks for rake_tasks, console and runner to avoid circular constant loading issues. diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb index 08cfe4f70d..cdf18f8080 100644 --- a/activerecord/lib/active_record/relation/finder_methods.rb +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -254,6 +254,7 @@ module ActiveRecord values = @klass.connection.distinct("#{@klass.connection.quote_table_name table_name}.#{primary_key}", orders) relation = relation.dup.select(values) + relation.uniq_value = nil id_rows = @klass.connection.select_all(relation.arel, 'SQL', relation.bind_values) ids_array = id_rows.map {|row| row[primary_key]} diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb index 21bd7b51d5..2efafe5c24 100644 --- a/activerecord/test/cases/finder_test.rb +++ b/activerecord/test/cases/finder_test.rb @@ -93,6 +93,18 @@ class FinderTest < ActiveRecord::TestCase assert !Topic.includes(:replies).limit(1).where('0 = 1').exists? end + def test_exists_with_distinct_association_includes_and_limit + author = Author.first + assert !author.unique_categorized_posts.includes(:special_comments).limit(0).exists? + assert author.unique_categorized_posts.includes(:special_comments).limit(1).exists? + end + + def test_exists_with_distinct_association_includes_limit_and_order + author = Author.first + assert !author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(0).exists? + assert author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(1).exists? + end + def test_exists_with_empty_table_and_no_args_given Topic.delete_all assert !Topic.exists? -- cgit v1.2.3