1 files changed, 58 insertions, 36 deletions

diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 24ca8b0be4..73761ed7ed 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -8,10 +8,8 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :_reflections, instance_writer: false
-      class_attribute :aggregate_reflections, instance_writer: false
-      self._reflections = {}
-      self.aggregate_reflections = {}
+      class_attribute :_reflections, instance_writer: false, default: {}
+      class_attribute :aggregate_reflections, instance_writer: false, default: {}
     end
 
     def self.create(macro, name, scope, options, ar)
@@ -173,7 +171,7 @@ module ActiveRecord
       JoinKeys = Struct.new(:key, :foreign_key) # :nodoc:
 
       def join_keys
-        get_join_keys klass
+        @join_keys ||= get_join_keys(klass)
       end
 
       # Returns a list of scopes that should be applied for this Reflection
@@ -187,10 +185,30 @@ module ActiveRecord
       end
       deprecate :scope_chain
 
+      def join_scope(table, foreign_table, foreign_klass)
+        predicate_builder = predicate_builder(table)
+        scope_chain_items = join_scopes(table, predicate_builder)
+        klass_scope       = klass_join_scope(table, predicate_builder)
+
+        key         = join_keys.key
+        foreign_key = join_keys.foreign_key
+
+        klass_scope.where!(table[key].eq(foreign_table[foreign_key]))
+
+        if klass.finder_needs_type_condition?
+          klass_scope.where!(klass.send(:type_condition, table))
+        end
+
+        if type
+          klass_scope.where!(type => foreign_klass.base_class.sti_name)
+        end
+
+        scope_chain_items.inject(klass_scope, &:merge!)
+      end
+
       def join_scopes(table, predicate_builder) # :nodoc:
         if scope
-          [ActiveRecord::Relation.create(klass, table, predicate_builder)
-            .instance_exec(&scope)]
+          [build_scope(table, predicate_builder).instance_exec(&scope)]
         else
           []
         end
@@ -199,20 +217,15 @@ module ActiveRecord
       def klass_join_scope(table, predicate_builder) # :nodoc:
         if klass.current_scope
           klass.current_scope.clone.tap { |scope|
-            scope.joins_values = []
+            scope.joins_values = scope.left_outer_joins_values = [].freeze
           }
         else
-          relation = ActiveRecord::Relation.create(
-            klass,
-            table,
-            predicate_builder,
-          )
-          klass.send(:build_default_scope, relation)
+          klass.default_scoped(build_scope(table, predicate_builder))
         end
       end
 
       def constraints
-        chain.map(&:scopes).flatten
+        chain.flat_map(&:scopes)
       end
 
       def counter_cache_column
@@ -289,7 +302,19 @@ module ActiveRecord
         JoinKeys.new(join_pk(association_klass), join_fk)
       end
 
+      def build_scope(table, predicate_builder = predicate_builder(table))
+        Relation.create(klass, table, predicate_builder)
+      end
+
+      protected
+        def actual_source_reflection # FIXME: this is a horrible name
+          self
+        end
+
       private
+        def predicate_builder(table)
+          PredicateBuilder.new(TableMetadata.new(klass, table))
+        end
 
         def join_pk(_)
           foreign_key
@@ -581,11 +606,9 @@ module ActiveRecord
         seed + [self]
       end
 
-      protected
-
-        def actual_source_reflection # FIXME: this is a horrible name
-          self
-        end
+      def extensions
+        Array(options[:extend])
+      end
 
       private
 
@@ -745,10 +768,6 @@ module ActiveRecord
     end
 
     class HasAndBelongsToManyReflection < AssociationReflection # :nodoc:
-      def initialize(name, scope, options, active_record)
-        super
-      end
-
       def macro; :has_and_belongs_to_many; end
 
       def collection?
@@ -759,7 +778,6 @@ module ActiveRecord
     # Holds all the metadata about a :through association as it was specified
     # in the Active Record class.
     class ThroughReflection < AbstractReflection #:nodoc:
-      attr_reader :delegate_reflection
       delegate :foreign_key, :foreign_type, :association_foreign_key,
                :active_record_primary_key, :type, :get_join_keys, to: :source_reflection
 
@@ -985,19 +1003,23 @@ module ActiveRecord
         collect_join_reflections(seed + [self])
       end
 
-      def collect_join_reflections(seed)
-        a = source_reflection.add_as_source seed
-        if options[:source_type]
-          through_reflection.add_as_polymorphic_through self, a
-        else
-          through_reflection.add_as_through a
+      # TODO Change this to private once we've dropped Ruby 2.2 support.
+      # Workaround for Ruby 2.2 "private attribute?" warning.
+      protected
+        attr_reader :delegate_reflection
+
+        def actual_source_reflection # FIXME: this is a horrible name
+          source_reflection.actual_source_reflection
         end
-      end
 
       private
-
-        def actual_source_reflection # FIXME: this is a horrible name
-          source_reflection.send(:actual_source_reflection)
+        def collect_join_reflections(seed)
+          a = source_reflection.add_as_source seed
+          if options[:source_type]
+            through_reflection.add_as_polymorphic_through self, a
+          else
+            through_reflection.add_as_through a
+          end
         end
 
         def primary_key(klass)
@@ -1105,7 +1127,7 @@ module ActiveRecord
       end
 
       def alias_name
-        Arel::Table.new(table_name)
+        Arel::Table.new(table_name, type_caster: klass.type_caster)
       end
 
       def all_includes; yield; end