title: Is Attribute Routing possible in Azure Functions
body: <p>I am trying to enforce a route parameter to be <code>guid</code> but getting below error</p>
  
  <blockquote>
    <p>"Exception while executing function: GetUser -> One or more errors
    occurred. -> Exception binding parameter 'req' -> Invalid cast from
    'System.String' to 'System.Guid'."</p>
  </blockquote>
  
  <pre><code>public static async Task&lt;HttpResponseMessage&gt; Run(
              [HttpTrigger(AuthorizationLevel.Admin, "get", Route = "GetUser/{userId:guid}")] HttpRequestMessage req,
              Guid userId, ILogger log)
          {
          }
  </code></pre>
  
  <p>The request i am making is <code>http://localhost:7071/api/GetUser/246fb962-604d-4699-9443-fa3fa840e9eb/</code></p>
  
  <p>Am i missing some thing? Cannot we enforce route parameter to be guid ?</p>