class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
end

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  # Dump from discourse application controller serialize data
  def serialize_data(obj, serializer, opts=nil)
    serializer_opts = opts || {}

    if obj.respond_to?(:to_ary)
      serializer_opts[:each_serializer] = serializer
      ActiveModel::ArraySerializer.new(obj.to_ary, serializer_opts).as_json
    else
      serializer.new(obj, serializer_opts).as_json
    end
  end
end

Backup serialize_data method from discourse application controller
Backup serialize_data method from discourse application controller
