Freeze casted values instead of original values in database queries

This deals with a problem introduced in #7743ab95b8e15581f432206245c691434a3993d1a751b9d451170956d59457a9R8
that was preventing query `Class` serialized attributes. Duplicating the original
`Class` argument generates an anonymous class that can't be serialized as YAML.

This change makes query attributes hasheable based on their frozen casted values
to prevent the problem.

This solution is based on an idea by @matthewd from rails#47338 (comment).

Author: jorgemanrubia

activemodel/lib/active_model/attribute.rb

@@ -115,13 +115,17 @@ def has_been_read?
     def ==(other)
       self.class == other.class &&
         name == other.name &&
-        value_before_type_cast == other.value_before_type_cast &&
+        identifier_value == other.identifier_value &&
         type == other.type
     end
     alias eql? ==
 
     def hash
-      [self.class, name, value_before_type_cast, type].hash
+      [self.class, name, identifier_value, type].hash
+    end
+
+    def identifier_value
+      value_before_type_cast
     end
 
     def init_with(coder)

activemodel/lib/active_model/type/helpers/mutable.rb

@@ -4,10 +4,6 @@ module ActiveModel
   module Type
     module Helpers # :nodoc: all
       module Mutable
-        def immutable_value(value)
-          value.deep_dup.freeze
-        end
-
         def cast(value)
           deserialize(serialize(value))
         end

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Fix error when querying serialized Class attributes.
+
+    *Jorge Manrubia*
+
 *   Add support for `Array#intersect?` to `ActiveRecord::Relation`.
 
     `Array#intersect?` is only available on Ruby 3.1 or later.

activerecord/lib/active_record/relation/predicate_builder.rb

@@ -66,7 +66,7 @@ def build(attribute, value, operator = nil)
 
     def build_bind_attribute(column_name, value)
       type = table.type(column_name)
-      Relation::QueryAttribute.new(column_name, type.immutable_value(value), type)
+      Relation::QueryAttribute.new(column_name, value, type)
     end
 
     def resolve_arel_attribute(table_name, column_name, &block)

activerecord/lib/active_record/relation/query_attribute.rb

@@ -36,10 +36,24 @@ def unboundable?
         @_unboundable
       end
 
+      def identifier_value
+        if unboundable?
+          super
+        else
+          # Override to define equality based on frozen casted values to prevent caching
+          # issues with mutable database query values.
+          value_for_database
+        end
+      end
+
       private
         def infinity?(value)
           value.respond_to?(:infinite?) && value.infinite?
         end
+
+        def _value_for_database
+          super.deep_dup.freeze
+        end
     end
   end
 end

activerecord/test/cases/serialized_attribute_test.rb

@@ -9,6 +9,11 @@
 class SerializedAttributeTest < ActiveRecord::TestCase
   def setup
     ActiveRecord.use_yaml_unsafe_load = true
+    @yaml_column_permitted_classes_default = ActiveRecord.yaml_column_permitted_classes
+  end
+
+  def teardown
+    ActiveRecord.yaml_column_permitted_classes = @yaml_column_permitted_classes_default
   end
 
   fixtures :topics, :posts
@@ -23,6 +28,10 @@ class ImportantTopic < Topic
     serialize :important, type: Hash
   end
 
+  class ClassifiedTopic < Topic
+    serialize :important, type: Class
+  end
+
   teardown do
     Topic.serialize("content")
   end
@@ -166,6 +175,14 @@ def test_serialized_string_attribute
     assert_equal(myobj, topic.content)
   end
 
+  def test_serialized_class_attribute
+    ActiveRecord.yaml_column_permitted_classes += [Class]
+
+    topic = ClassifiedTopic.create(important: Symbol).reload
+    assert_equal(Symbol, topic.important)
+    assert_not_empty ClassifiedTopic.where(important: Symbol)
+  end
+
   def test_nil_serialized_attribute_without_class_constraint
     topic = Topic.new
     assert_nil topic.content
@@ -551,6 +568,7 @@ def test_serialized_attribute_works_under_concurrent_initial_access
 
 class SerializedAttributeTestWithYamlSafeLoad < SerializedAttributeTest
   def setup
+    super
     ActiveRecord.use_yaml_unsafe_load = false
   end