> Wouldn't participant.events.destroy_all # sets all participant_id fields in associated events to NULL also delete the the Event record? 

`:dependent => :nullify` alters that behavior:


```ruby
class User < ActiveRecord::Base
  has_many :posts, :dependent => :nullify
end

class Post < ActiveRecord::Base
  belongs_to :user
end

u = User.create
5.times { u.posts.create }
u.destroy
Post.count == 5 # => true
Post.first.user_id # => nil
```