title: how to handle query string parameter in asp.net web api
body: <p>here is how I have routing setup.</p>
  
  <pre><code> routes.MapHttpRoute(
                          name: "Authors",
                          routeTemplate: "api/authors",
                          defaults: new { controller = "authors" }
                      );
  </code></pre>
  
  <p>controller action method</p>
  
  <pre><code>// GET /api/authors/
      public string GetAuthors(string author_ids)
      {
          return data;
      }
  </code></pre>
  
  <p>Url <a href="http://site.com/api/authors?author_ids=1" rel="nofollow">http://site.com/api/authors?author_ids=1</a> actually calls controller action but when I don't pass querystring parameter, it says no controller action matching found.  </p>
  
  <p>How to handle optional querystring parameter when defining route?  </p>