don't transmit full record on change - only send changed values about hyperstack HOT 2 OPEN

module ReactiveRecord
  class Broadcast

    def self.after_commit(operation, model)
      # Calling public_columns_hash once insures all policies are loaded
      # before the first broadcast.
      @public_columns_hash ||= ActiveRecord::Base.public_columns_hash
      Hyperstack::InternalPolicy.regulate_broadcast(model) do |data|
        # filter out any unchanged fields unless its a create operation in which case we want to send everything
        # allowed by the policies.
        filter_unchanged_fields!(model.class.primary_key.to_sym, data) if operation != :create
        puts "Broadcast aftercommit hook: #{data}" if Hyperstack::Connection.show_diagnostics

        if !Hyperstack.on_server? && Hyperstack::Connection.root_path
          send_to_server(operation, data, model.__synchromesh_update_time) rescue nil # fails if server no longer running so ignore
        else
          SendPacket.run(data, operation: operation, updated_at: model.__synchromesh_update_time)
        end
      end
    rescue ActiveRecord::StatementInvalid => e
      raise e unless e.message == "Could not find table 'hyperstack_connections'"
    end unless RUBY_ENGINE == 'opal'

    def self.filter_unchanged_fields!(primary_key, data)
      data[:record] = data[:record].filter do |field, _| 
        data[:previous_changes].key?(field) || field == primary_key
      end
    end unless RUBY_ENGINE == 'opal'
....