Merge pull request rails#41012 from kamipo/fix_complicated_through_as…

…sociation

Fix complicated has_many through with nested where condition

activerecord/lib/active_record/associations/association_scope.rb

@@ -131,11 +131,14 @@ def add_constraints(scope, owner, chain)
               if scope_chain_item == chain_head.scope
                 scope.merge! item.except(:where, :includes, :unscope, :order)
               elsif !item.references_values.empty?
-                join_dependency = item.construct_join_dependency(
-                  item.eager_load_values | item.includes_values, Arel::Nodes::OuterJoin
-                )
-                scope.joins!(*item.joins_values, join_dependency)
-                scope.left_outer_joins!(*item.left_outer_joins_values)
+                scope.joins_values |= item.joins_values
+                scope.left_outer_joins_values |= item.left_outer_joins_values
+
+                associations = item.eager_load_values | item.includes_values
+
+                unless associations.empty?
+                  scope.joins_values << item.construct_join_dependency(associations, Arel::Nodes::OuterJoin)
+                end
               end
 
               reflection.all_includes do

activerecord/lib/active_record/relation/query_methods.rb

@@ -1140,7 +1140,7 @@ def build_where_clause(opts, rest = []) # :nodoc:
           self.references_values |= references unless references.empty?
 
           parts = predicate_builder.build_from_hash(opts) do |table_name|
-            lookup_reflection_from_join_dependencies(table_name)
+            lookup_table_klass_from_join_dependencies(table_name)
           end
         when Arel::Nodes::Node
           parts = [opts]
@@ -1153,9 +1153,9 @@ def build_where_clause(opts, rest = []) # :nodoc:
       alias :build_having_clause :build_where_clause
 
     private
-      def lookup_reflection_from_join_dependencies(table_name)
+      def lookup_table_klass_from_join_dependencies(table_name)
         each_join_dependencies do |join|
-          return join.reflection if table_name == join.table_name
+          return join.base_klass if table_name == join.table_name
         end
         nil
       end
@@ -1366,7 +1366,7 @@ def arel_column(field)
         elsif field.match?(/\A\w+\.\w+\z/)
           table, column = field.split(".")
           predicate_builder.resolve_arel_attribute(table, column) do
-            lookup_reflection_from_join_dependencies(table)
+            lookup_table_klass_from_join_dependencies(table)
           end
         else
           yield field

activerecord/lib/active_record/table_metadata.rb

@@ -33,10 +33,13 @@ def associated_table(table_name)
         return self
       end
 
-      reflection ||= yield table_name if block_given?
+      if reflection
+        association_klass = reflection.klass unless reflection.polymorphic?
+      elsif block_given?
+        association_klass = yield table_name
+      end
 
-      if reflection && !reflection.polymorphic?
-        association_klass = reflection.klass
+      if association_klass
         arel_table = association_klass.arel_table
         arel_table = arel_table.alias(table_name) if arel_table.name != table_name
         TableMetadata.new(association_klass, arel_table, reflection)

activerecord/test/cases/associations/has_many_through_associations_test.rb

@@ -66,6 +66,14 @@ def test_through_association_with_left_joins
     assert_equal [comments(:eager_other_comment1)], authors(:mary).comments.merge(Post.left_joins(:comments))
   end
 
+  def test_through_association_with_through_scope_and_nested_where
+    company = Company.create!(name: "special")
+    developer = SpecialDeveloper.create!
+    SpecialContract.create!(company: company, special_developer: developer)
+
+    assert_equal [developer], company.special_developers.where.not("contracts.id": nil)
+  end
+
   def test_preload_with_nested_association
     posts = Post.where(id: [authors(:david).id, authors(:mary).id]).
       preload(:author, :author_favorites_with_scope).order(:id).to_a

activerecord/test/models/company.rb

@@ -13,6 +13,8 @@ class Company < AbstractCompany
   has_one :dummy_account, foreign_key: "firm_id", class_name: "Account"
   has_many :contracts
   has_many :developers, through: :contracts
+  has_many :special_contracts, -> { includes(:special_developer).where.not("developers.id": nil) }
+  has_many :special_developers, through: :special_contracts
 
   alias_attribute :new_name, :name
   attribute :metadata, :json

activerecord/test/models/contract.rb

@@ -30,3 +30,9 @@ def update_metadata
 class NewContract < Contract
   validates :company_id, presence: true
 end
+
+class SpecialContract < ActiveRecord::Base
+  self.table_name = "contracts"
+  belongs_to :company
+  belongs_to :special_developer, foreign_key: "developer_id"
+end

activerecord/test/models/developer.rb

@@ -114,6 +114,11 @@ def track_instance_count
 class SubDeveloper < Developer
 end
 
+class SpecialDeveloper < ActiveRecord::Base
+  self.table_name = "developers"
+  has_many :special_contracts, foreign_key: "developer_id"
+end
+
 class SymbolIgnoredDeveloper < ActiveRecord::Base
   self.table_name = "developers"
   self.ignored_columns = [:first_name, :last_name]