title: React-router Link, pass in params
body: <p>If you have a route such as: </p>
  
  <pre><code>&lt;Route path="/users/:userId" /&gt;
  </code></pre>
  
  <p>And then you export that route, and so it can be used across your app, such as:</p>
  
  <pre><code>export const MY_ROUTE = '/users/:userId/';
  
  &lt;Route path={MY_ROUTE} /&gt;
  </code></pre>
  
  <p>How do you set the param in a link dynamically? i.e. I would like to do this:</p>
  
  <pre><code>&lt;Link to={MY_ROUTE} params={{userId: 1}} /&gt;
  </code></pre>
  
  <p>but params is totally ignored... and query just makes a query (?userId=) not a param... any ideas?</p>