title: Update attribute with array insertion
body: <p>I have an <code>Impression</code> model with an <code>actions</code> attribute that is serialized for <code>Array</code>.</p>
  
  <pre><code>class Impression &lt; ActiveRecord::Base
    serialize :actions, Array
  end
  </code></pre>
  
  <p>Normal attribute updating procedure:<br>
  <code>impression.update(some_attr: "new_value")</code></p>
  
  <p>Normal array insertion procedure:<br>
  <code>impression.actions &lt;&lt; "new_value"</code><br>
  <code>impression.save</code></p>
  
  <p>Is there a way to insert a new value to an array attribute that works like the <code>.update</code> method, i.e. in one single expression?</p>