Allow multiple decorations which can be used by such like `EncryptedType`

activerecord/lib/active_record/attribute_methods/serialization.rb

@@ -128,11 +128,12 @@ module ActiveRecord
             Coders::YAMLColumn.new(attr_name, class_name_or_coder)
           end
 
-          decorate_attribute_type(attr_name.to_s, **options) do |cast_type|
+          attribute(attr_name, **options) do |cast_type|
             if type_incompatible_with_serialize?(cast_type, class_name_or_coder)
               raise ColumnNotSerializableError.new(attr_name, cast_type)
             end
 
+            cast_type = cast_type.subtype if Type::Serialized === cast_type
             Type::Serialized.new(cast_type, coder)
           end
         end

activerecord/lib/active_record/attributes.rb

@@ -208,14 +208,30 @@ module ActiveRecord
       # tracking is performed. The methods +changed?+ and +changed_in_place?+
       # will be called from ActiveModel::Dirty. See the documentation for those
       # methods in ActiveModel::Type::Value for more details.
-      def attribute(name, cast_type = nil, **options, &block)
+      def attribute(name, cast_type = nil, default: NO_DEFAULT_PROVIDED, **options, &block)
         name = name.to_s
         reload_schema_from_cache
 
+        case cast_type
+        when Symbol
+          type = cast_type
+          cast_type = -> _ { Type.lookup(type, **options, adapter: Type.adapter_name_from(self)) }
+        when nil
+          if (prev_cast_type, prev_default = attributes_to_define_after_schema_loads[name])
+            default = prev_default if default == NO_DEFAULT_PROVIDED
+
+            cast_type = if block_given?
+              -> subtype { yield Proc === prev_cast_type ? prev_cast_type[subtype] : prev_cast_type }
+            else
+              prev_cast_type
+            end
+          else
+            cast_type = block || -> subtype { subtype }
+          end
+        end
+
         self.attributes_to_define_after_schema_loads =
-          attributes_to_define_after_schema_loads.merge(
-            name => [cast_type || block, options]
-          )
+          attributes_to_define_after_schema_loads.merge(name => [cast_type, default])
       end
 
       # This is the low level API which sits beneath +attribute+. It only
@@ -248,8 +264,9 @@ module ActiveRecord
 
       def load_schema! # :nodoc:
         super
-        attributes_to_define_after_schema_loads.each do |name, (type, options)|
-          define_attribute(name, _lookup_cast_type(name, type, options), **options.slice(:default))
+        attributes_to_define_after_schema_loads.each do |name, (cast_type, default)|
+          cast_type = cast_type[type_for_attribute(name)] if Proc === cast_type
+          define_attribute(name, cast_type, default: default)
         end
       end
 
@@ -272,32 +289,6 @@ module ActiveRecord
           end
           _default_attributes[name] = default_attribute
         end
-
-        def decorate_attribute_type(attr_name, **default)
-          type, options = attributes_to_define_after_schema_loads[attr_name]
-
-          default.with_defaults!(default: options[:default]) if options&.key?(:default)
-
-          attribute(attr_name, **default) do |cast_type|
-            if type && !type.is_a?(Proc)
-              cast_type = _lookup_cast_type(attr_name, type, options)
-            end
-
-            yield cast_type
-          end
-        end
-
-        def _lookup_cast_type(name, type, options)
-          case type
-          when Symbol
-            adapter_name = ActiveRecord::Type.adapter_name_from(self)
-            ActiveRecord::Type.lookup(type, **options.except(:default), adapter: adapter_name)
-          when Proc
-            type[type_for_attribute(name)]
-          else
-            type || type_for_attribute(name)
-          end
-        end
     end
   end
 end

activerecord/lib/active_record/enum.rb

@@ -153,8 +153,10 @@ module ActiveRecord
         end
       end
 
+      attr_reader :subtype
+
       private
-        attr_reader :name, :mapping, :subtype
+        attr_reader :name, :mapping
     end
 
     def enum(definitions)
@@ -181,7 +183,8 @@ module ActiveRecord
 
         attr = attribute_alias?(name) ? attribute_alias(name) : name
 
-        decorate_attribute_type(attr, **default) do |subtype|
+        attribute(attr, **default) do |subtype|
+          subtype = subtype.subtype if EnumType === subtype
           EnumType.new(attr, enum_values, subtype)
         end
 

activerecord/test/cases/attributes_test.rb

@@ -68,6 +68,15 @@ module ActiveRecord
       assert_equal "the overloaded default", klass.new.overloaded_string_with_limit
     end
 
+    test "attributes with overridden types keep their type when a default value is configured separately" do
+      child = Class.new(OverloadedType) do
+        attribute :overloaded_float, default: "123"
+      end
+
+      assert_equal OverloadedType.type_for_attribute("overloaded_float"), child.type_for_attribute("overloaded_float")
+      assert_equal 123, child.new.overloaded_float
+    end
+
     test "extra options are forwarded to the type caster constructor" do
       klass = Class.new(OverloadedType) do
         attribute :starts_at, :datetime, precision: 3, limit: 2, scale: 1, default: -> { Time.now.utc }
@@ -295,6 +304,15 @@ module ActiveRecord
       assert_equal 123, model.non_existent_decimal
     end
 
+    test "attributes not backed by database columns keep their type when a default value is configured separately" do
+      child = Class.new(OverloadedType) do
+        attribute :non_existent_decimal, default: "123"
+      end
+
+      assert_equal OverloadedType.type_for_attribute("non_existent_decimal"), child.type_for_attribute("non_existent_decimal")
+      assert_equal 123, child.new.non_existent_decimal
+    end
+
     test "attributes not backed by database columns properly interact with mutation and dirty" do
       child = Class.new(ActiveRecord::Base) do
         self.table_name = "topics"

activerecord/test/cases/serialized_attribute_test.rb

@@ -442,6 +442,18 @@ class SerializedAttributeTest < ActiveRecord::TestCase
     ActiveRecord::Type.registry = old_registry
   end
 
+  def test_decorated_type_with_decorator_block
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = Topic.table_name
+      store :content
+      attribute(:content) { |subtype| EncryptedType.new(subtype: subtype) }
+    end
+
+    topic = klass.create!(content: { trial: true })
+
+    assert_equal({ "trial" => true }, topic.content)
+  end
+
   def test_mutation_detection_does_not_double_serialize
     coder = Object.new
     def coder.dump(value)