osem-fcy/app/controllers/api/v1/conferences_controller.rb

class Api::V1::ConferencesController < Api::BaseController
  respond_to :json

  def index
    if params[:conference_id].blank?
      conferences = Conference.all
    else
      conferences = Conference.find_all_by_guid(params[:conference_id])
    end
    render json: conferences, serializer: ConferencesArraySerializer
  end
end