Transform model calls to queries in migrations to not run into enum e…

…rror

db/migrate/20150728084536_add_event_participation_states.rb

@@ -11,15 +11,32 @@ def up
     unless column_exists?(:event_participations, :state)
       add_column(:event_participations, :state, :string, limit: 60)
 
-      course_participations =
-        Event::Participation.joins(:event).
-                             where(events: { type: Event::Course.sti_name })
-      course_participations.where(active: true).update_all(state: :assigned)
-      course_participations.where(active: false).update_all(state: :applied)
-    end
+      connection = ActiveRecord::Base.connection
+      set_assigned = <<-SQL
+      UPDATE events 
+      SET state = 'assigned' 
+      WHERE id IN 
+        (
+        SELECT events.id FROM event_participations AS participations
+        JOIN events ON participations.event_id = events.id
+        WHERE events.type = 'Event::Course' AND participations.active = true
+        )
+      SQL
+
+      set_applied = <<-SQL
+      UPDATE events 
+      SET state = 'applied' 
+      WHERE id IN 
+        (
+        SELECT events.id FROM event_participations AS participations
+        JOIN events ON participations.event_id = events.id
+        WHERE events.type = 'Event::Course' AND participations.active = false
+        )
+      SQL
 
-    Event::Participation.reset_column_information
-    Event.reset_column_information # to make new column appear
+      connection.execute(set_assigned)
+      connection.execute(set_applied)
+    end
 
     # Recalculate the counts of all events
     Event.find_each { |e| e.refresh_participant_counts! }