title: undefined method `distance_of_time_in_words'
body: <p>I have two questions about undefined method `distance_of_time_in_words'</p>
  
  <p>In my view I am attempting this, and get undefined method:</p>
  
  <pre><code>&lt;td&gt;&lt;%= distance_of_time_in_words (patient_course_step.started, patient_course_step.completed) %&gt;&lt;/td&gt;
  </code></pre>
  
  <p>I really want to use this in my model to create a "helper method" for my model.</p>
  
  <p>Examples of helper methods in model:</p>
  
  <pre><code>def duration
     distance_of_time_in_words (self.started, self.completed)
  end
  
  def status
      if started.nil?
        created_at_formated = created_at.strftime("%B %d, %Y, %l:%M %p")
        return "Not started assigned on #{created_at_formated}"
      elsif !completed.nil?
        completed_formated = completed.strftime("%B %d, %Y, %l:%M %p")
        return "Completed at #{completed_formated}"
      else
        last_viewed_formated = last_viewed.strftime("%B %d, %Y, %l:%M %p")
        return "In Progress, last viewed at #{last_viewed_formated}"
      end
    end
  </code></pre>
  
  <ol>
  <li>How can I get distance_of_time_in_words to work in my view</li>
  <li>Is it a good practice to have helper methods in a model (as shown above)</li>
  </ol>