`update_column` take ruby-land input, not database-land input

In the case of serialized columns, we would expect the unserialized
value as input, not the serialized value. The original issue which made
this distinction, #14163, introduced a bug. If you passed serialized
input to the method, it would double serialize when it was sent to the
database. You would see the wrong input upon reloading, or get an error
if you had a specific type on the serialized column.

To put it another way, `update_column` is a special case of
`update_all`, which would take `['a']` and not `['a'].to_yaml`, but you
would not pass data from `params` to it.

Fixes #18037

4 files changed, 27 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 8cc1904575..88536eaac0 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -9,6 +9,10 @@ module ActiveRecord
         FromUser.new(name, value, type)
       end
 
+      def with_cast_value(name, value, type)
+        WithCastValue.new(name, value, type)
+      end
+
       def null(name)
         Null.new(name)
       end
@@ -58,6 +62,10 @@ module ActiveRecord
       self.class.from_database(name, value, type)
     end
 
+    def with_cast_value(value)
+      self.class.with_cast_value(name, value, type)
+    end
+
     def type_cast(*)
       raise NotImplementedError
     end
@@ -93,6 +101,16 @@ module ActiveRecord
       end
     end
 
+    class WithCastValue < Attribute # :nodoc:
+      def type_cast(value)
+        value
+      end
+
+      def changed_in_place_from?(old_value)
+        false
+      end
+    end
+
     class Null < Attribute # :nodoc:
       def initialize(name)
         super(name, nil, Type::Value.new)
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index b3c8209a74..16804f86bf 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -73,7 +73,7 @@ module ActiveRecord
         if should_type_cast
           @attributes.write_from_user(attr_name, value)
         else
-          @attributes.write_from_database(attr_name, value)
+          @attributes.write_cast_value(attr_name, value)
         end
 
         value
diff --git a/activerecord/lib/active_record/attribute_set.rb b/activerecord/lib/active_record/attribute_set.rb
index 6b1d7ea79e..66fcaf6945 100644
--- a/activerecord/lib/active_record/attribute_set.rb
+++ b/activerecord/lib/active_record/attribute_set.rb
@@ -39,6 +39,10 @@ module ActiveRecord
       attributes[name] = self[name].with_value_from_user(value)
     end
 
+    def write_cast_value(name, value)
+      attributes[name] = self[name].with_cast_value(value)
+    end
+
     def freeze
       @attributes.freeze
       super
diff --git a/activerecord/test/cases/serialized_attribute_test.rb b/activerecord/test/cases/serialized_attribute_test.rb
index 66f345d805..56a0e92e1d 100644
--- a/activerecord/test/cases/serialized_attribute_test.rb
+++ b/activerecord/test/cases/serialized_attribute_test.rb
@@ -243,8 +243,9 @@ class SerializedAttributeTest < ActiveRecord::TestCase
     t = Topic.create(content: "first")
     assert_equal("first", t.content)
 
-    t.update_column(:content, Topic.type_for_attribute('content').type_cast_for_database("second"))
-    assert_equal("second", t.content)
+    t.update_column(:content, ["second"])
+    assert_equal(["second"], t.content)
+    assert_equal(["second"], t.reload.content)
   end
 
   def test_serialized_column_should_unserialize_after_update_attribute
@@ -253,5 +254,6 @@ class SerializedAttributeTest < ActiveRecord::TestCase
 
     t.update_attribute(:content, "second")
     assert_equal("second", t.content)
+    assert_equal("second", t.reload.content)
   end
 end