title: Changing behavior in an existing model class in Rails (inside Redmine) - How to load it?
body: <p>I am building a plugin for Redmine and I have to calculate the cost of some Issues based on some customized fields. </p>
  
  <p>So I made a change to class Issue (the original is a model class defined in Redmine itself) creating a "cost" method.</p>
  
  <pre><code>class Issue &lt; ActiveRecord::Base
      def cost 
        return 100
      end   
  end
  </code></pre>
  
  <p>The point here is how to load this change. I've tried to create a <em>"issue.rb"</em> in my <em>"models"</em> folder but the method remained unseen by views. So i appended this class definition to plugin's <em>"init.rb"</em> and it worked, but I feel this is not the right place to leave this code. My question is: <strong>What is the "right" way to load this Issue extension to be recognized in the whole app?</strong></p>