title: How to use has_key? method in rails?
body: <p>I want to check if a key 'test' is include or not in a hash with rails. I tried <code>has_key?</code>('test') method but following error occur.
  
  <blockquote>
    <p>undefined method `has_key?'</p>
  </blockquote>
  
  <p><br> How to check if key is include or not? <br>
  Thanks in advance.</p>