fix undefined method eq for Arel::Nodes::Equality by deep call left

lib/ransack/adapters/active_record/context.rb

@@ -163,7 +163,7 @@ module Ransack
         def build_correlated_subquery(association)
           join_constraints = extract_joins(association)
           join_root = join_constraints.shift
-          correlated_key = join_root.right.expr.left
+          correlated_key = extract_correlated_key(join_root)
           subquery = Arel::SelectManager.new(association.base_klass)
           subquery.from(join_root.left)
           subquery.project(correlated_key)
@@ -179,6 +179,18 @@ module Ransack
 
         private
 
+        def extract_correlated_key(join_root)
+          correlated_key = join_root.right.expr.left
+
+          if correlated_key.is_a? Arel::Nodes::And
+            correlated_key = correlated_key.left.left
+          elsif correlated_key.is_a? Arel::Nodes::Equality
+            correlated_key = correlated_key.left
+          else
+            correlated_key
+          end
+        end
+
         def get_parent_and_attribute_name(str, parent = @base)
           attr_name = nil
 

spec/ransack/adapters/active_record/context_spec.rb

@@ -40,6 +40,47 @@ module Ransack
           end
         end
 
+        describe '#build_correlated_subquery' do
+          it 'build correlated subquery for Root STI model' do
+            search = Search.new(Person, { articles_title_not_eq: 'some_title' }, context: subject)
+            attribute = search.conditions.first.attributes.first
+            constraints = subject.build_correlated_subquery(attribute.parent).constraints
+            constraint = constraints.first
+
+            expect(constraints.length).to eql 1
+            expect(constraint.left.name).to eql 'person_id'
+            expect(constraint.left.relation.name).to eql 'articles'
+            expect(constraint.right.name).to eql 'id'
+            expect(constraint.right.relation.name).to eql 'people'
+          end
+
+          it 'build correlated subquery for Child STI model when predicate is not_eq' do
+            search = Search.new(Person, { story_articles_title_not_eq: 'some_title' }, context: subject)
+            attribute = search.conditions.first.attributes.first
+            constraints = subject.build_correlated_subquery(attribute.parent).constraints
+            constraint = constraints.first
+
+            expect(constraints.length).to eql 1
+            expect(constraint.left.relation.name).to eql 'articles'
+            expect(constraint.left.name).to eql 'person_id'
+            expect(constraint.right.relation.name).to eql 'people'
+            expect(constraint.right.name).to eql 'id'
+          end
+
+          it 'build correlated subquery for Child STI model when predicate is eq' do
+            search = Search.new(Person, { story_articles_title_not_eq: 'some_title' }, context: subject)
+            attribute = search.conditions.first.attributes.first
+            constraints = subject.build_correlated_subquery(attribute.parent).constraints
+            constraint = constraints.first
+
+            expect(constraints.length).to eql 1
+            expect(constraint.left.relation.name).to eql 'articles'
+            expect(constraint.left.name).to eql 'person_id'
+            expect(constraint.right.relation.name).to eql 'people'
+            expect(constraint.right.name).to eql 'id'
+          end
+        end
+
         describe 'sharing context across searches' do
           let(:shared_context) { Context.for(Person) }
 

spec/support/schema.rb

@@ -29,6 +29,8 @@ class Person < ActiveRecord::Base
   belongs_to :parent, class_name: 'Person', foreign_key: :parent_id
   has_many   :children, class_name: 'Person', foreign_key: :parent_id
   has_many   :articles
+  has_many   :story_articles
+
   has_many :published_articles, ->{ where(published: true) },
       class_name: "Article"
   has_many   :comments
@@ -136,6 +138,9 @@ class Article < ActiveRecord::Base
   default_scope { where("'default_scope' = 'default_scope'") }
 end
 
+class StoryArticle < Article
+end
+
 class Recommendation < ActiveRecord::Base
   belongs_to :person
   belongs_to :target_person, class_name: 'Person'
@@ -194,6 +199,7 @@ module Schema
         t.string   :title
         t.text     :subject_header
         t.text     :body
+        t.string   :type
         t.boolean  :published, default: true
       end