Fix marshalling for virtual attributes on ActiveType::Object and ActiveType::Record

Author: martinschaflitzl1

lib/active_type/marshalling.rb

@@ -0,0 +1,62 @@
+module ActiveType
+  module Marshalling
+    # With 7.1 rails defines its own marshal_dump and marshal_load methods,
+    # which selectively only dump and load the record´s attributes and some more stuff, but not our @virtual_attributes.
+    # Whether these new methods are actually used, depends on ActiveRecord::Marshalling.format_version
+    # For format_version = 6.1 active record uses the default ruby implementation for dumping and loading.
+    # For format_version = 7.1 active record uses a custom implementation, which we need to override.
+    #
+    # format_version can also be dynamically changed during runtime, on change we need to define or undefine our marshal_dump dynamically, because:
+    # * We cannot check the format_version at runtime within marshal_dump or marshal_load,
+    #   as we can´t just super to the default for the wrong version, because there is no method to super to.
+    #   (The default implementation is a ruby internal, not a real method.)
+    # * We cannot override the methods at load time only when format version is 7.1,
+    #   because format version usually gets set after our initialisation and could change at any time.
+    #
+    # Two facts about ruby also help us with that (also see https://ruby-doc.org/core-2.6.8/Marshal.html):
+    # * A custom marshal_load is only used, when marshal_dump is also defined. So we can keep marshal_dump always defined.
+    #   (If either is missing, ruby will use _dump and _load)
+    # * If a serialized object is dumped using _dump it will be loaded using _load, never marshal_load, so a record
+    #   serialized with format_version = 6.1 using _dump, will always load using _load, ignoring whether marshal_load is defined or not.
+    #   This ensures objects will always be deserialized with the method they were serialized with. We don´t need to worry about that.
+
+    class << self
+      attr_reader :format_version
+
+      def format_version=(version)
+        case version
+        when 6.1
+          Methods.remove_method(:marshal_dump) if Methods.method_defined?(:marshal_dump)
+        when 7.1
+          Methods.alias_method(:marshal_dump, :_marshal_dump_7_1)
+        else
+          raise ArgumentError, "Unknown marshalling format: #{version.inspect}"
+        end
+        @format_version = version
+      end
+    end
+
+    module ActiveRecordMarshallingExtension
+      def format_version=(version)
+        ActiveType::Marshalling.format_version = version
+        super(version)
+      end
+    end
+
+    module Methods
+      def _marshal_dump_7_1
+        [super, @virtual_attributes]
+      end
+
+      def marshal_load(state)
+        super_attributes, @virtual_attributes = state
+        super(super_attributes)
+      end
+    end
+
+  end
+end
+
+ActiveRecord::Marshalling.singleton_class.prepend(ActiveType::Marshalling::ActiveRecordMarshallingExtension)
+# Set ActiveType´s format_version to ActiveRecord´s, in case ActiveRecord uses the default value, which is set before we are loaded.
+ActiveType::Marshalling.format_version = ActiveRecord::Marshalling.format_version

lib/active_type/object.rb

@@ -1,6 +1,7 @@
 require 'active_type/no_table'
 require 'active_type/virtual_attributes'
 require 'active_type/nested_attributes'
+require 'active_type/marshalling' if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
 
 module ActiveType
 
@@ -9,6 +10,7 @@ class Object < ActiveRecord::Base
     include NoTable
     include VirtualAttributes
     include NestedAttributes
+    include Marshalling::Methods if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
 
   end
 

lib/active_type/record.rb

@@ -2,6 +2,7 @@
 require 'active_type/record_extension'
 require 'active_type/nested_attributes'
 require 'active_type/change_association'
+require 'active_type/marshalling' if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
 
 module ActiveType
 
@@ -13,6 +14,7 @@ class Record < ActiveRecord::Base
     include NestedAttributes
     include RecordExtension
     include ChangeAssociation
+    include Marshalling::Methods if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
 
   end
 

spec/active_type/object_spec.rb

@@ -531,4 +531,81 @@ class ObjectWithUnsupportedTypes < Object
     end
   end
 
+  describe "marshalling" do
+    shared_examples "marshalling attributes" do
+      it "marshals attributes properly" do
+        object = ObjectSpec::Object.create(
+          virtual_string: "foobar",
+          virtual_integer: 123,
+          virtual_time: Time.parse("12:00 15.10.2025"),
+          virtual_date: Date.parse("15.10.2025"),
+          virtual_boolean: true,
+          virtual_attribute: { some: "random object" },
+          virtual_type_attribute: "ObjectSpec::Object::PlainObject",
+        )
+
+        serialized_object = Marshal.dump(object)
+        deserialized_object = Marshal.load(serialized_object)
+
+        expect(deserialized_object.virtual_string).to eq "foobar"
+        expect(deserialized_object.virtual_integer).to eq 123
+        expect(deserialized_object.virtual_time).to eq Time.parse("12:00 15.10.2025")
+        expect(deserialized_object.virtual_date).to eq Date.parse("15.10.2025")
+        expect(deserialized_object.virtual_boolean).to eq true
+        expect(deserialized_object.virtual_attribute).to eq({ some: "random object" })
+        expect(deserialized_object.virtual_type_attribute).to eq "ObjectSpec::Object::PlainObject"
+      end
+    end
+
+    if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
+      context 'for 6.1 marshalling' do
+        before do
+          ActiveRecord::Marshalling.format_version = 6.1
+        end
+
+        include_examples "marshalling attributes"
+      end
+
+      context 'for 7.1 marshalling' do
+        before do
+          ActiveRecord::Marshalling.format_version = 7.1
+        end
+
+        include_examples "marshalling attributes"
+      end
+
+      describe "loading a object marshalled with format version 6.1, but the current version is 7.1" do
+        it "marshals attributes properly" do
+          object = ObjectSpec::Object.create(virtual_attribute: "foobar")
+
+          ActiveRecord::Marshalling.format_version = 6.1
+          serialized_object = Marshal.dump(object)
+
+          ActiveRecord::Marshalling.format_version = 7.1
+          deserialized_object = Marshal.load(serialized_object)
+
+          expect(deserialized_object.virtual_attribute).to eq "foobar"
+        end
+      end
+
+      describe "loading a object marshalled with format version 7.1, but the current version is 6.1" do
+        it "marshals attributes properly" do
+          object = ObjectSpec::Object.create(virtual_attribute: "foobar")
+
+          ActiveRecord::Marshalling.format_version = 7.1
+          serialized_object = Marshal.dump(object)
+
+          ActiveRecord::Marshalling.format_version = 6.1
+          deserialized_object = Marshal.load(serialized_object)
+
+          expect(deserialized_object.virtual_attribute).to eq "foobar"
+        end
+      end
+
+    else
+      include_examples "marshalling attributes"
+    end
+
+  end
+
 end

spec/active_type/record_spec.rb

@@ -376,4 +376,88 @@ class RecordWithOptionalBelongsToFlippedValidatesForeignKey < Record
     end
   end
 
+  describe "marshalling" do
+    shared_examples "marshalling attributes" do
+      it "marshals attributes properly" do
+        object = RecordSpec::Record.create!(
+          virtual_string: "foobar",
+          virtual_integer: 123,
+          virtual_time: Time.parse("12:00 15.10.2025"),
+          virtual_date: Date.parse("15.10.2025"),
+          virtual_boolean: true,
+          virtual_attribute: { some: "random object" },
+          virtual_type_attribute: "RecordSpec::Record",
+          persisted_string: "a real active record attribute"
+        )
+
+        serialized_object = Marshal.dump(object)
+        deserialized_object = Marshal.load(serialized_object)
+
+        expect(deserialized_object.virtual_string).to eq "foobar"
+        expect(deserialized_object.virtual_integer).to eq 123
+        expect(deserialized_object.virtual_time).to eq Time.parse("12:00 15.10.2025")
+        expect(deserialized_object.virtual_date).to eq Date.parse("15.10.2025")
+        expect(deserialized_object.virtual_boolean).to eq true
+        expect(deserialized_object.virtual_attribute).to eq({ some: "random object" })
+        expect(deserialized_object.virtual_type_attribute).to eq "RecordSpec::Record"
+        expect(deserialized_object.persisted_string).to eq "a real active record attribute"
+      end
+    end
+
+    if ActiveRecord::VERSION::MAJOR >= 7 && ActiveRecord::VERSION::MINOR >= 1
+      context 'for 6.1 marshalling' do
+        before do
+          ActiveRecord::Marshalling.format_version = 6.1
+        end
+
+        include_examples "marshalling attributes"
+      end
+
+      context 'for 7.1 marshalling' do
+        before do
+          ActiveRecord::Marshalling.format_version = 7.1
+        end
+
+        include_examples "marshalling attributes"
+      end
+
+      describe "loading a object marshalled with format version 6.1, but the current version is 7.1" do
+        it "marshals attributes properly" do
+          object = RecordSpec::Record.create!(
+            virtual_string: "foo",
+            persisted_string: "bar"
+          )
+
+          ActiveRecord::Marshalling.format_version = 6.1
+          serialized_object = Marshal.dump(object)
+
+          ActiveRecord::Marshalling.format_version = 7.1
+          deserialized_object = Marshal.load(serialized_object)
+
+          expect(deserialized_object.virtual_string).to eq "foo"
+          expect(deserialized_object.persisted_string).to eq "bar"
+        end
+      end
+
+      describe "loading a object marshalled with format version 7.1, but the current version is 6.1" do
+        it "marshals attributes properly" do
+          object = RecordSpec::Record.create!(
+            virtual_string: "foo",
+            persisted_string: "bar"
+          )
+
+          ActiveRecord::Marshalling.format_version = 7.1
+          serialized_object = Marshal.dump(object)
+
+          ActiveRecord::Marshalling.format_version = 6.1
+          deserialized_object = Marshal.load(serialized_object)
+
+          expect(deserialized_object.virtual_string).to eq "foo"
+          expect(deserialized_object.persisted_string).to eq "bar"
+        end
+      end
+    else
+      include_examples "marshalling attributes"
+    end
+  end
 end