Extract all `base_class.name` as `polymorphic_name`

This is an alternative of #29722, and follow up of #32048.

This does not change the current behavior, but makes it easier to modify
all polymorphic names consistently.

8 files changed, 43 insertions, 23 deletions

diff --git a/activerecord/lib/active_record/associations/association.rb b/activerecord/lib/active_record/associations/association.rb
index 364f1fe74f..ca8c7794e0 100644
--- a/activerecord/lib/active_record/associations/association.rb
+++ b/activerecord/lib/active_record/associations/association.rb
@@ -201,8 +201,8 @@ module ActiveRecord
           if (reflection.has_one? || reflection.collection?) && !options[:through]
             attributes[reflection.foreign_key] = owner[reflection.active_record_primary_key]
 
-            if reflection.options[:as]
-              attributes[reflection.type] = owner.class.base_class.name
+            if reflection.type
+              attributes[reflection.type] = owner.class.polymorphic_name
             end
           end
 
diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index ad41ec8d2f..0a90a6104a 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -35,12 +35,12 @@ module ActiveRecord
 
         binds << last_reflection.join_id_for(owner)
         if last_reflection.type
-          binds << owner.class.base_class.name
+          binds << owner.class.polymorphic_name
         end
 
         chain.each_cons(2).each do |reflection, next_reflection|
           if reflection.type
-            binds << next_reflection.klass.base_class.name
+            binds << next_reflection.klass.polymorphic_name
           end
         end
         binds
@@ -63,7 +63,7 @@ module ActiveRecord
           scope = apply_scope(scope, table, key, value)
 
           if reflection.type
-            polymorphic_type = transform_value(owner.class.base_class.name)
+            polymorphic_type = transform_value(owner.class.polymorphic_name)
             scope = apply_scope(scope, table, reflection.type, polymorphic_type)
           end
 
@@ -84,7 +84,7 @@ module ActiveRecord
           constraint = table[key].eq(foreign_table[foreign_key])
 
           if reflection.type
-            value = transform_value(next_reflection.klass.base_class.name)
+            value = transform_value(next_reflection.klass.polymorphic_name)
             scope = apply_scope(scope, table, reflection.type, value)
           end
 
diff --git a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
index 55d789c66a..75b4c4481a 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -13,7 +13,7 @@ module ActiveRecord
 
         def replace_keys(record)
           super
-          owner[reflection.foreign_type] = record ? record.class.base_class.name : nil
+          owner[reflection.foreign_type] = record ? record.class.polymorphic_name : nil
         end
 
         def different_target?(record)
diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb
index 71c8f6df58..0f38d6bbda 100644
--- a/activerecord/lib/active_record/associations/preloader/association.rb
+++ b/activerecord/lib/active_record/associations/preloader/association.rb
@@ -117,7 +117,7 @@ module ActiveRecord
             scope = klass.scope_for_association
 
             if reflection.type
-              scope.where!(reflection.type => model.base_class.name)
+              scope.where!(reflection.type => model.polymorphic_name)
             end
 
             scope.merge!(reflection_scope) if reflection.scope
diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb
index 77cfb36b25..208ba95c52 100644
--- a/activerecord/lib/active_record/inheritance.rb
+++ b/activerecord/lib/active_record/inheritance.rb
@@ -156,6 +156,10 @@ module ActiveRecord
         store_full_sti_class ? name : name.demodulize
       end
 
+      def polymorphic_name
+        base_class.name
+      end
+
       def inherited(subclass)
         subclass.instance_variable_set(:@_type_candidates_cache, Concurrent::Map.new)
         super
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 42b451241d..2f43d005f3 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -193,7 +193,7 @@ module ActiveRecord
         klass_scope       = klass_join_scope(table, predicate_builder)
 
         if type
-          klass_scope.where!(type => foreign_klass.base_class.name)
+          klass_scope.where!(type => foreign_klass.polymorphic_name)
         end
 
         scope_chain_items.inject(klass_scope, &:merge!)
diff --git a/activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb b/activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb
index a5e9a0473e..aae04d9348 100644
--- a/activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb
@@ -22,19 +22,21 @@ module ActiveRecord
 
         def type_to_ids_mapping
           default_hash = Hash.new { |hsh, key| hsh[key] = [] }
-          values.each_with_object(default_hash) { |value, hash| hash[base_class(value).name] << convert_to_id(value) }
+          values.each_with_object(default_hash) do |value, hash|
+            hash[klass(value).polymorphic_name] << convert_to_id(value)
+          end
         end
 
         def primary_key(value)
-          associated_table.association_join_primary_key(base_class(value))
+          associated_table.association_join_primary_key(klass(value))
         end
 
-        def base_class(value)
+        def klass(value)
           case value
           when Base
-            value.class.base_class
+            value.class
           when Relation
-            value.klass.base_class
+            value.klass
           end
         end
 
diff --git a/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb b/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
index 4776e11128..5fca972aee 100644
--- a/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
+++ b/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
@@ -8,6 +8,10 @@ module Namespaced
   class Post < ActiveRecord::Base
     self.table_name = "posts"
     has_one :tagging, as: :taggable, class_name: "Tagging"
+
+    def self.polymorphic_name
+      sti_name
+    end
   end
 end
 
@@ -25,34 +29,44 @@ module PolymorphicFullStiClassNamesSharedTest
   end
 
   def test_class_names
-    ActiveRecord::Base.store_full_sti_class = false
+    ActiveRecord::Base.store_full_sti_class = !store_full_sti_class
     post = Namespaced::Post.find_by_title("Great stuff")
-    assert_equal @tagging, post.tagging
+    assert_nil post.tagging
 
-    ActiveRecord::Base.store_full_sti_class = true
+    ActiveRecord::Base.store_full_sti_class = store_full_sti_class
     post = Namespaced::Post.find_by_title("Great stuff")
     assert_equal @tagging, post.tagging
   end
 
   def test_class_names_with_includes
-    ActiveRecord::Base.store_full_sti_class = false
+    ActiveRecord::Base.store_full_sti_class = !store_full_sti_class
     post = Namespaced::Post.includes(:tagging).find_by_title("Great stuff")
-    assert_equal @tagging, post.tagging
+    assert_nil post.tagging
 
-    ActiveRecord::Base.store_full_sti_class = true
+    ActiveRecord::Base.store_full_sti_class = store_full_sti_class
     post = Namespaced::Post.includes(:tagging).find_by_title("Great stuff")
     assert_equal @tagging, post.tagging
   end
 
   def test_class_names_with_eager_load
-    ActiveRecord::Base.store_full_sti_class = false
+    ActiveRecord::Base.store_full_sti_class = !store_full_sti_class
     post = Namespaced::Post.eager_load(:tagging).find_by_title("Great stuff")
-    assert_equal @tagging, post.tagging
+    assert_nil post.tagging
 
-    ActiveRecord::Base.store_full_sti_class = true
+    ActiveRecord::Base.store_full_sti_class = store_full_sti_class
     post = Namespaced::Post.eager_load(:tagging).find_by_title("Great stuff")
     assert_equal @tagging, post.tagging
   end
+
+  def test_class_names_with_find_by
+    post = Namespaced::Post.find_by_title("Great stuff")
+
+    ActiveRecord::Base.store_full_sti_class = !store_full_sti_class
+    assert_nil Tagging.find_by(taggable: post)
+
+    ActiveRecord::Base.store_full_sti_class = store_full_sti_class
+    assert_equal @tagging, Tagging.find_by(taggable: post)
+  end
 end
 
 class PolymorphicFullStiClassNamesTest < ActiveRecord::TestCase