title: Web Api 2 empty string parameter GET
body: <p>i have setup the route to be:
  [Route("{id}/users/search/{search}")]
  and the associated action is:
  SomeAction(int id, string text)</p>
  
  <p>The service has the following function.
  for the resource with id={id} and the users of this resource get the users that match with the {search} term (username, email etc).</p>
  
  <p>the {search} can have a value so the service returns only the matching entities or does not have a value (empty string or null) so the service returns everything.</p>
  
  <p>For the part with a value it works fine.
  For the second part i cannot find something to set the get request that matches the empty string.</p>
  
  <p>i tried the following:
  1/users/search/null {search} = "null"
  1/users/search/ does not match route
  1/users/search does not match route</p>
  
  <p>has anyone a hint how this could be done?</p>
  
  <p>Update: i have tried to replace the action:
  SomeAction(int id, string text)
  with:
  SomeAction(Model model) where model is</p>
  
  <pre><code>public class ApplicationUserSearchModel
  {
      [Required]
      public int Id { get; set; }
      [Required(AllowEmptyStrings = true)]
      public string MatchText { get; set; }
  }
  </code></pre>
  
  <p>with no luck since i don't know what to send in order to match the url to this.</p>