[1381] Refactor approval_status removal migration [v5.5]

db/migrate/20150405012126_remove_approval_status_from_reservation.rb

@@ -1,45 +1,81 @@
 class RemoveApprovalStatusFromReservation < ActiveRecord::Migration
+  # for use in the flag_res method, based off of Reservation model in v5.5.0
+  FLAGS = { request: (1 << 1), missed_email_sent: (1 << 5) }
+
+  # similarly, based off the Reservation model enums in v5.5.0
+  STATUSES =
+    %w(requested reserved denied checked_out missed returned archived)
+      .each_with_index.to_h
+
   def change
-    Reservation.transaction do
-      Reservation.all.each do |res|
-        if res.approval_status == 'approved'
-          res.flag(:request)
-        elsif res.approval_status == 'missed_and_emailed'
-          res.flag(:missed_email_sent)
+    # store ActiveRecord connection to run queries
+    conn = ActiveRecord::Base.connection
+
+    # go through all reservations
+    conn.exec_query('select * from reservations').each do |res|
+      new_flags = res['flags']
+      if res['approval_status'] == 'approved'
+        new_flags = flag_res(new_flags, :request)
+      elsif res['approval_status'] == 'missed_and_emailed'
+        new_flags = flag_res(new_flags, :missed_email_sent)
+      end
+
+      if res['checked_in']
+        new_status = STATUSES['returned']
+        if Time.zone.at(res['checked_in']) >
+          (res['due_date'] + 1.day).beginning_of_day
+          new_overdue = true
+        end
+        if res['notes'].try(:include?, 'Archived')
+          new_status = STATUSES['archived']
+        end
+      elsif res['checked_out']
+        new_status = STATUSES['checked_out']
+        if (res['due_date'] + 1.day).beginning_of_day < Time.zone.today
+          new_overdue = true
         end
+      elsif res['start_date'].beginning_of_day < Time.zone.today
+        new_status = STATUSES['missed']
+      elsif res['approval_status'] == 'requested'
+        new_flags = flag_res(new_flags, :request)
+        new_status = STATUSES['requested']
+      elsif res['approval_status'] == 'denied'
+        new_flags = flag_res(new_flags, :request)
+        new_status = STATUSES['denied']
+      elsif 'approved auto'.include? res['approval_status']
+        new_status = STATUSES['reserved']
+      else
+        # catch any unusual reservations
+        new_flags = flag_res(new_flags, :request)
+        new_status = STATUSES['requested']
+      end
+
+      # see if the flags actually changed
+      new_flags = (new_flags == res['flags']) ? nil : new_flags
 
-        if res.checked_in
-          res.status = 'returned'
-          if res.checked_in > (res.due_date + 1.day)
-            res.overdue = true
-          end
-          if res.notes.try(:include?, 'Archived')
-            res.status = 'archived'
-          end
-        elsif res.checked_out
-          res.status = 'checked_out'
-          if (res.due_date + 1.day) < Time.zone.today
-            res.overdue = true
-          end
-        elsif res.start_date < Time.zone.today
-          res.status = 'missed'
-        elsif res.approval_status == 'requested'
-          res.flag(:request)
-          res.status = 'requested'
-        elsif res.approval_status == 'denied'
-          res.flag(:request)
-          res.status = 'denied'
-        elsif 'approved auto'.include? res.approval_status
-          res.status = 'reserved'
-        else
-          # catch any unusual reservations
-          res.flag(:request)
-          res.status = 'requested'
+      # make sure we have something to update
+      if new_status || new_flags || new_overdue
+        update_str = 'UPDATE reservations SET'
+        update_str << " status = '#{new_status}'" if new_status
+        if new_flags
+          update_str << "#{new_status ? ',' : ''} flags = #{new_flags}"
+        end
+        if new_overdue
+          update_str << "#{(new_status || new_flags) ? ',' : ''} overdue = 1"
         end
-        res.save!(validate: false)
+        update_str << " WHERE reservations.id = #{res['id']}"
+
+        # actually run update
+        conn.execute(update_str)
       end
     end
 
     remove_column :reservations, :approval_status, :string
   end
+
+  # based on the Reservation#flag instance method in v5.5.0 - this allows us to
+  # decouple the migration from the actual model
+  def flag_res(old_flags, new_flag)
+    old_flags | FLAGS[new_flag]
+  end
 end