title: Rails Controller - getting the index action to display only certain records
body: <p>By default the rails controller will load all associated objects in the index action.  What I would like to do is display only certain objects.</p>
  
  <p>For example</p>
  
  <p>I have a model called Car(id, make, model, year).  I want list only particular makes in the index, depending on a parameter.</p>
  
  <p>There are a few ways to do this, I'm just not sure which is best.</p>
  
  <p>I could:</p>
  
  <p>pass a parameter to the link:</p>
  
  <pre><code>cars_path(make: 'Acura') 
  </code></pre>
  
  <p>and would give me /cars/?make=Acura</p>
  
  <p>set up routes: (this seems to get messy)</p>
  
  <pre><code>match "cars/:make" =&gt; "cars#index", constraints: {make: /[A-z]{1,20}/}
  </code></pre>
  
  <p>or I could make a separate controller action for this</p>
  
  <p>Any suggestion about what is the most "rails-y" way to do this?  RoR 3.1</p>