Finished 'Attribute Routing with Optional Parameter'

2_Routing.md

@@ -293,8 +293,31 @@ Now `http://localhost:xxxx/students/2/courses` will be routed to `GetStudentCour
 * controller action method have `[Route]` attribute use Attribute Routing
 * controller action method without `[Route]` attribute uses Convention-based routing.
 
-## Attribute Routing in ASP.NET MVC
-
 ## Attribute Routing with Optional Parameter
 
+URI parameter can also be defined in attribute routing by adding **question mark ("?")** to router parameter within `{}`. We can also specify default value by **parameter = value** 
+
+e.g. optional URI Parameter `{studentName? }`
+
+```csharp
+        // Optional URI Parameter
+        // URL: /MVCTest/
+        // URL: /MVCTest/Pranaya
+        [Route("MVCTest/{studentName ?}")]
+        public ActionResult MVC(string studentName)
+        {
+            DoSth(studentName);
+            return View();
+        }
+        // Optional URI Parameter with default value
+        // URL: /WEBAPITest/
+        // URL: /WEBAPITest/Pranaya
+        [Route("WEBAPITest/{studentName = Pranaya}")]
+        public ActionResult WEBAPI(string studentName)
+        {
+            DoSth(studentName);
+            return View();
+        }
+```
+
 ## Route Prefix in Attribute Routing