Create EventTypes with data from existing Events

Use the STI column used until this moment to create new EventTypes and
assign them to their corresponding Events.

db/migrate/20150416234411_create_event_types_for_all_existing_events.rb

@@ -0,0 +1,18 @@
+class CreateEventTypesForAllExistingEvents < ActiveRecord::Migration
+  def up
+    event_types = execute 'SELECT DISTINCT(events.type) as type_name, tracks.conference_id, events.created_at, events.updated_at FROM events INNER JOIN tracks ON tracks.id = events.track_id WHERE events.type NOT NULL GROUP BY type_name;'
+
+    event_types.each do |type|
+      execute "INSERT INTO event_types (conference_id, created_at, updated_at)
+               VALUES (#{type['conference_id']}, '#{type['created_at']}', '#{type['updated_at']}');"
+
+      event_type_id = execute('SELECT MAX(id) AS last_id FROM event_types;').first['last_id']
+
+      execute "INSERT INTO event_type_translations (event_type_id, locale, created_at, updated_at, name, description)
+               VALUES (#{event_type_id}, 'en', '#{type['created_at']}', '#{type['created_at']}', '#{type['type_name']}', 'None');"
+    end
+  end
+
+  def down
+  end
+end

db/migrate/20150417002119_add_event_type_to_events.rb

@@ -0,0 +1,5 @@
+class AddEventTypeToEvents < ActiveRecord::Migration
+  def change
+    add_reference :events, :event_type, index: true, foreign_key: true
+  end
+end

db/migrate/20150417002233_populate_event_type_of_existing_events.rb

@@ -0,0 +1,14 @@
+class PopulateEventTypeOfExistingEvents < ActiveRecord::Migration
+  def up
+    event_ids = execute('SELECT id FROM events WHERE type NOT NULL;').map { |row| row['id'] };
+
+    event_ids.each do |id|
+      event_type_id = execute("SELECT ett.event_type_id FROM events JOIN event_type_translations AS ett ON events.type = ett.name WHERE events.id = #{id};").first['event_type_id']
+      execute("UPDATE events SET event_type_id = #{event_type_id} WHERE id = #{id}");
+    end
+  end
+
+  def down
+    execute("UPDATE events SET event_type_id = NULL");
+  end
+end