core/app/models/spree/shipping_category.rb
module Spree
class ShippingCategory < Spree::Base
include Spree::UniqueName
if defined?(Spree::Webhooks::HasWebhooks)
include Spree::Webhooks::HasWebhooks
end
with_options inverse_of: :shipping_category do
has_many :products
has_many :shipping_method_categories
end
has_many :shipping_methods, through: :shipping_method_categories
end
end