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Referencing a table via the ON condition in a join should force that …

…table to be eager-loaded via a JOIN rather than via subsequent queries.
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1 parent 9cee693 commit 532f915037ab65873c433e30399d11f93df9f1f8 @jonleighton jonleighton committed with tenderlove Mar 7, 2011
Showing with 27 additions and 1 deletion.
  1. +12 −1 activerecord/lib/active_record/relation.rb
  2. +15 −0 activerecord/test/cases/relations_test.rb
@@ -407,8 +407,19 @@ def method_missing(method, *args, &block)
private
def references_eager_loaded_tables?
+ joined_tables = arel.join_sources.map do |join|
+ if join.is_a?(Arel::Nodes::StringJoin)
+ tables_in_string(join.left)
+ else
+ [join.left.table_name, join.left.table_alias]
+ end
+ end
+
+ joined_tables += [table.name, table.table_alias]
+
# always convert table names to downcase as in Oracle quoted table names are in uppercase
- joined_tables = (tables_in_string(arel.join_sql) + [table.name, table.table_alias]).compact.map{ |t| t.downcase }.uniq
+ joined_tables = joined_tables.flatten.compact.map { |t| t.downcase }.uniq
+
(tables_in_string(to_sql) - joined_tables).any?
end
@@ -850,4 +850,19 @@ def test_removing_limit_with_options
def test_primary_key
assert_equal "id", Post.scoped.primary_key
end
+
+ def test_eager_loading_with_conditions_on_joins
+ scope = Post.includes(:comments)
+
+ # This references the comments table, and so it should cause the comments to be eager
+ # loaded via a JOIN, rather than by subsequent queries.
+ scope = scope.joins(
+ Post.arel_table.create_join(
+ Post.arel_table,
+ Post.arel_table.create_on(Comment.arel_table[:id].eq(3))
+ )
+ )
+
+ assert scope.eager_loading?
+ end
end

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