Allow an event to have more than one speaker

app/models/event.rb

@@ -10,6 +10,7 @@ class Event < ActiveRecord::Base
   has_one :conference, through: :track
   belongs_to :user # XXX: Transition to candidate_speaker
   belongs_to :candidate_speaker, class_name: 'User', foreign_key: 'user_id'
+  has_and_belongs_to_many :speakers, class_name: 'SpeakerProfile'
 
   after_create :send_new_event_notification
 

db/migrate/20141013134153_create_events_to_speakers_join_table.rb

@@ -0,0 +1,12 @@
+class CreateEventsToSpeakersJoinTable < ActiveRecord::Migration
+  def up
+    create_join_table :events, :speaker_profiles
+    Event.all.each do |event|
+      event.speakers << event.user.speaker_profile if event.user.speaker_profile.present?
+    end
+  end
+
+  def down
+    drop_table :events_speaker_profiles
+  end
+end