title: Create RouteValueDictionary with multivalued keys
body: <p>I'd like to return a <code>RedirectToRouteResult</code> that sends users to a URL like the following:</p>
  
  <pre><code>/MyController/MyAction/id?newid=3&amp;newid=5&amp;newid=7
  </code></pre>
  
  <p>The <code>newid</code> parameter has several values.</p>
  
  <p>My call looks like: <code>return RedirectToAction(string.Empty, routeValues);</code></p>
  
  <p>Here is what I have tried so far, and that do not work:</p>
  
  <pre><code>// ...?newid%5B0%5D=3&amp;newid%5B1%5D=5&amp;newid%5B2%5D=7
  var routeValues = new RouteValueDictionary {
      {"id", myid},
      {"newid[0]", 3},
      {"newid[1]", 5},
      {"newid[2]", 7},
  };
  
  // ...?newid=System.Int32%5B%5D
  var routeValues = new { id = myid, newid = new int[] { 3, 5, 7 } };
  
  // ...?newid=System.String%5B%5D
  var routeValues = new { id = myid, newid = new string[] { "3", "5", "7" } };
  
  // ...?newid=System.Int32%5B%5D
  var routeValues = new RouteValueDictionary {
      {"id", myid},
      {"newid", new int[] { 3, 5, 7 } }
  };
  </code></pre>
  
  <p>What is the secret to make this work?</p>