Enable backwards compatibility — no serialization case

Co-authored-by: Szymon Fiedler <szymon.fiedler@gmail.com>

Author: mostlyobvious

ruby_event_store-active_record/lib/ruby_event_store/active_record/event_repository.rb

@@ -7,9 +7,30 @@ class EventRepository
 
       def initialize(model_factory: WithDefaultModels.new, serializer:)
         @serializer = serializer
-
         @event_klass, @stream_klass = model_factory.call
-        @event_klass.include(SkipJsonSerialization)
+        if serializer == NULL && json_data_type?
+          warn <<~MSG
+            The data or metadata column is of a JSON/B type and expects a JSON string. 
+
+            Yet the repository serializer is configured as #{serializer} and it would not 
+            produce the expected JSON string. 
+
+            In ActiveRecord there's an implicit serialization to JSON for JSON/B column types 
+            that made it work so far. This behaviour is unfortunately also a source of undesired 
+            double serialization — first in the EventRepository, second in the ActiveRecord.
+            
+            In the past we've advised workarounds that introduced configuration incosistency 
+            with other data types and serialization formats, i.e. explicitly passing NULL serializer 
+            just for the JSON/B data types.
+
+            As of now this special ActiveRecord behaviour is disabled. You should be using JSON 
+            serializer back again:
+
+            RubyEventStore::ActiveRecord::EventRepository.new(serializer: JSON)
+          MSG
+        else
+          @event_klass.include(SkipJsonSerialization)
+        end
         @repo_reader = EventRepositoryReader.new(@event_klass, @stream_klass, serializer)
         @index_violation_detector = IndexViolationDetector.new(@event_klass.table_name, @stream_klass.table_name)
       end
@@ -164,6 +185,12 @@ def append_to_stream_(records, stream, expected_version)
         end
         add_to_stream(event_ids, stream, expected_version) { @event_klass.insert_all!(hashes) }
       end
+
+      private
+
+      def json_data_type?
+        %i[data metadata].any? { |attr| @event_klass.column_for_attribute(attr).type.start_with?("json") }
+      end
     end
   end
 end

ruby_event_store-active_record/spec/event_repository_spec.rb

@@ -283,6 +283,34 @@ module ActiveRecord
         )
       end
 
+      specify "JSON/B backwards compatibility — explicit NULL serializer as advised before introduction of JSONClient" do
+        skip unless %w[json jsonb].include?(ENV["DATA_TYPE"])
+
+        expect { repository = EventRepository.new(serializer: NULL) }.to output(<<~MSG).to_stderr
+          The data or metadata column is of a JSON/B type and expects a JSON string. 
+
+          Yet the repository serializer is configured as RubyEventStore::NULL and it would not 
+          produce the expected JSON string. 
+
+          In ActiveRecord there's an implicit serialization to JSON for JSON/B column types 
+          that made it work so far. This behaviour is unfortunately also a source of undesired 
+          double serialization — first in the EventRepository, second in the ActiveRecord.
+          
+          In the past we've advised workarounds that introduced configuration incosistency 
+          with other data types and serialization formats, i.e. explicitly passing NULL serializer 
+          just for the JSON/B data types.
+
+          As of now this special ActiveRecord behaviour is disabled. You should be using JSON 
+          serializer back again:
+
+          RubyEventStore::ActiveRecord::EventRepository.new(serializer: JSON)
+        MSG
+
+        expect {
+          repository.append_to_stream([SRecord.new], Stream.new("stream"), ExpectedVersion.any)
+        }.not_to raise_error
+      end
+
       private
 
       def with_precision(time)