title: I have a Roles association, need a contains method?
body: <p>I have a User model that has a Roles collection.</p>
  
  <p>The Roles collection has columns like:</p>
  
  <pre><code>id, name, ....
  </code></pre>
  
  <p>I am now looping through another collection, and I would to create a new collection if the role_id's match, so:</p>
  
  <pre><code>SomeOtherCollection.each do |i|
  
  @blah &lt;&lt; i  if self.Roles.contains i.role_id
  
  end
  </code></pre>
  
  <p>Contains doesn't exist, how can I do this?</p>
  
  <p>The faster method the better since this will happen allot.</p>