You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: activity_map_cells_controller.rb
    path of file: ./repos/ekylibre/app/controllers/backend/cells
    
    the code of the file until where you have to start completion: module Backend
  module Cells
    class ActivityMapCellsContr
    
      def show
        @campaigns = if params[:campaign_ids]
                       Campaign.find(params[:campaign_ids])
                     elsif params[:campaign_id]
                       Campaign.find(params[:campaign_id])
                     else
                       current_campaign
                     end