taking advantage of the JoinSource node in the SQL AST

2 files changed, 8 insertions, 17 deletions

diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 906ad7699c..8bc28c06cb 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -187,7 +187,7 @@ module ActiveRecord
 
     def find_with_associations
       including = (@eager_load_values + @includes_values).uniq
-      join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, including, nil)
+      join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, including, [])
       rows = construct_relation_for_association_find(join_dependency).to_a
       join_dependency.instantiate(rows)
     rescue ThrowResult
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 51a39be065..67a94cec85 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -191,27 +191,19 @@ module ActiveRecord
     def custom_join_ast(table, joins)
       joins = joins.reject { |join| join.blank? }
 
-      return if joins.empty?
+      return [] if joins.empty?
 
       @implicit_readonly = true
 
-      joins.map! do |join|
+      joins.map do |join|
         case join
         when Array
           join = Arel.sql(join.join(' ')) if array_of_strings?(join)
         when String
           join = Arel.sql(join)
         end
-        join
+        table.create_string_join(join)
       end
-
-      head = table.create_string_join(table, joins.shift)
-
-      joins.inject(head) do |ast, join|
-        ast.right = table.create_string_join(ast.right, join)
-      end
-
-      head
     end
 
     def collapse_wheres(arel, wheres)
@@ -256,9 +248,9 @@ module ActiveRecord
       stashed_association_joins = joins.grep(ActiveRecord::Associations::ClassMethods::JoinDependency::JoinAssociation)
 
       non_association_joins = (joins - association_joins - stashed_association_joins)
-      join_ast = custom_join_ast(manager.froms.first, non_association_joins)
+      join_list = custom_join_ast(manager, non_association_joins)
 
-      join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, association_joins, join_ast)
+      join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, association_joins, join_list)
 
       join_dependency.graft(*stashed_association_joins)
 
@@ -269,10 +261,9 @@ module ActiveRecord
         association.join_to(manager)
       end
 
-      return manager unless join_ast
+      return manager unless join_list
 
-      join_ast.left = manager.froms.first
-      manager.from join_ast
+      join_list.each { |j| manager.from j }
       manager
     end