Custom default order order in active_admin

active_admin.rb

# initializers/active_admin.rb
module ActiveAdmin
  class OrderClause
    alias_method :initialize_old, :initialize
    alias_method :valid_old?, :valid?
    alias_method :to_sql_old, :to_sql
 
    def initialize(clause)
      if clause.class == String
        initialize_old(clause)
      else
        @clause = clause[:sql]
      end
    end
 
    def valid?
      if @clause
        @clause.present?
      else
        valid_old?
      end
    end
 
    def to_sql(active_admin_config)
      if @clause
        @clause
      else
        to_sql_old(active_admin_config)
      end
    end
  end
end

product.rb

# admin/product.rb
 
ActiveAdmin.register Product do
 
  config.sort_order = { sql: "shipments.shipment_date ASC, products.name ASC" }
 
end