WIP: ProxyOrders don't require an order, calculating total for serialized proxy orders from standing order where order does not exist

app/models/standing_line_item.rb

@@ -12,5 +12,9 @@ class StandingLineItem < ActiveRecord::Base
     .any?
   end
 
+  def total_estimate
+    (price_estimate || 0) * (quantity || 0)
+  end
+
   default_scope order('id ASC')
 end

app/serializers/api/admin/proxy_order_serializer.rb

@@ -2,7 +2,11 @@ class Api::Admin::ProxyOrderSerializer < ActiveModel::Serializer
   attributes :id, :state, :edit_path, :number, :completed_at, :order_cycle_id, :total
 
   def total
-    object.total.to_money.to_s
+    if object.total.present?
+      object.total.to_money.to_s
+    else
+      object.standing_order.standing_line_items.sum(&:total_estimate)
+    end
   end
 
   def completed_at