title: Possible to limit list of params when using React Router?
body: <p>Using React with React-Router in a project and am wondering if it's possible to limit the possibilities for param names, like so:</p>
  
  <pre><code>www.mydomain.com/books/:id
  </code></pre>
  
  <p>and allowing 'Catcher in the Rye' and 'To Kill A Mockingbird' to be passed through, like so:</p>
  
  <pre><code>www.mydomain.com/books/catcher-in-the-rye
  www.mydomain.com/books/to-kill-a-mocking-bird
  </code></pre>
  
  <p>I want to say that only a specific set of books can be used in place of :id (just so someone can't type in www.mydomain.com/books/whatever-they-want and have an empty React component render).</p>
  
  <p>I do currently have a '*' route that catches anything not mentioned, but because params are dynamically generated based on whatever is passed, that won't help in this case.</p>
  
  <p>Is this possible? Thanks.</p>