title: Rails has_one / has_many, dependent option: What values are available?
body: <p>I get the following error in Rails 4:</p>
  <p><code>dependent option must be one of destroy delete</code></p>
  <p>Per <a href="https://github.com/rails/rails/issues/3458" rel="nofollow noreferrer">https://github.com/rails/rails/issues/3458</a>, other options were supported in older versions. But what is possible nowadays?
  I could not find any other documentation.</p>