backup_deals.rb

shop = root.shops.first
products = shop.products(collections: "deals", class: "product").full_set

file = 'backup_variants_deals.csv'
columns = ["sku", "regular_price", "sale_price"]

data = CSV.generate do |csv|
  csv << columns
  products.each do |product|
    variants = product.variants
    variants.each do |variant|
      csv << [variant.sku, variant.regular_price, variant.sale_price]
    end
  end
end

File.write(file, data)
puts "#{file} <-- OK!"