check.rb

#!/usr/bin/env ruby

require "bundler/inline"
require "json"

gemfile do
  source "https://rubygems.org"
  gem "rails_event_store", "2.9.1"
  gem "railties", "~> 7.0.0"
end

IssueHasBeenPostedOnGithub = 
  Class.new(RailsEventStore::Event)

event = 
  IssueHasBeenPostedOnGithub.new(data: OpenStruct.new(message: "This is unpreserved OpenStruct."))

in_memory_repository_with_json_serialization_to_mimic_database_behaviour = 
  RubyEventStore::InMemoryRepository.new(serializer: JSON)   

preserve_types_as_seen_in_json_client =
  RubyEventStore::Mappers::Transformation::PreserveTypes
    .new 
    .register(Symbol, serializer: ->(v) { v.to_s }, deserializer: ->(v) { v.to_sym })
    .register(
      Time,
      serializer: ->(v) { v.iso8601(RubyEventStore::TIMESTAMP_PRECISION) },
      deserializer: ->(v) { Time.iso8601(v) }
    )
    .register(
      ActiveSupport::TimeWithZone,
      serializer: ->(v) { v.iso8601(RubyEventStore::TIMESTAMP_PRECISION) },
      deserializer: ->(v) { Time.iso8601(v).in_time_zone },
      stored_type: ->(*) { "ActiveSupport::TimeWithZone" }
    )
    .register(Date, serializer: ->(v) { v.iso8601 }, deserializer: ->(v) { Date.iso8601(v) })
    .register(DateTime, serializer: ->(v) { v.iso8601 }, deserializer: ->(v) { DateTime.iso8601(v) })
    .register(BigDecimal, serializer: ->(v) { v.to_s }, deserializer: ->(v) { BigDecimal(v) })

mapper_with_open_struct_preservation =
  RubyEventStore::Mappers::PipelineMapper.new(
    RubyEventStore::Mappers::Pipeline.new(
      preserve_types_as_seen_in_json_client.register(OpenStruct, serializer: ->(v) { v.to_h }, deserializer: ->(v) { OpenStruct.new(v) }),
      RubyEventStore::Mappers::Transformation::SymbolizeMetadataKeys.new
    )
  )

client = 
  RailsEventStore::Client.new(
    repository: in_memory_repository_with_json_serialization_to_mimic_database_behaviour,
    mapper: mapper_with_open_struct_preservation
  )
client.publish(event)

pp in_memory_repository_with_json_serialization_to_mimic_database_behaviour.instance_variable_get(:@storage)

pp [event.data, client.read.last.data]