Use named scope for finding line_items in a set of orders

app/models/spree/line_item_decorator.rb

@@ -36,6 +36,10 @@ Spree::LineItem.class_eval do
     end
   }
 
+  scope :in_orders, lambda { |orders|
+    where(order_id: orders)
+  }
+
   # Find line items that are from order sorted by variant name and unit value
   scope :sorted_by_name_and_unit_value, -> {
     joins(variant: :product).

lib/open_food_network/reports/line_items.rb

@@ -12,9 +12,7 @@ module OpenFoodNetwork
       end
 
       def list(line_item_includes = nil)
-        line_items = @order_permissions.
-          visible_line_items.
-          merge(Spree::LineItem.where(order_id: orders.result))
+        line_items = @order_permissions.visible_line_items.in_orders(orders.result)
 
         if @params[:supplier_id_in].present?
           line_items = line_items.supplied_by_any(@params[:supplier_id_in])