Fixing bug in optional route parameter binding

Author: mathewc

sample/HttpTrigger-CSharp-CustomRoute/run.csx

@@ -13,7 +13,7 @@ public class ProductInfo
 
 public static ProductInfo Run(ProductInfo info, string category, int? id, TraceWriter log)
 {
-    log.Info($"ProductInfo: Category={category} Id={id}");
+    log.Info($"ProductInfo: Category={info.Category} Id={info.Id}");
     log.Info($"Parameters: category={category} id={id}");
 
     return info;

src/WebJobs.Script.WebHost/WebScriptHostManager.cs

@@ -347,25 +347,28 @@ public FunctionDescriptor GetHttpFunctionOrNull(HttpRequestMessage request)
             if (routeData != null)
             {
                 _httpFunctions.TryGetValue(routeData.Route, out function);
+                AddRouteDataToRequest(routeData, request);
+            }
+
+            return function;
+        }
 
-                Dictionary<string, object> routeDataValues = null;
-                if (routeData.Values != null)
+        internal static void AddRouteDataToRequest(IHttpRouteData routeData, HttpRequestMessage request)
+        {
+            if (routeData.Values != null)
+            {
+                Dictionary<string, object> routeDataValues = new Dictionary<string, object>();
+                foreach (var pair in routeData.Values)
                 {
-                    routeDataValues = new Dictionary<string, object>();
-                    foreach (var pair in routeData.Values)
-                    {
-                        // filter out any unspecified optional parameters
-                        if (pair.Value != RouteParameter.Optional)
-                        {
-                            routeDataValues.Add(pair.Key, pair.Value);
-                        }
-                    }
+                    // translate any unspecified optional parameters to null values
+                    // unspecified values still need to be included as part of binding data
+                    // for correct binding to occur
+                    var value = pair.Value != RouteParameter.Optional ? pair.Value : null;
+                    routeDataValues.Add(pair.Key, value);
                 }
 
                 request.Properties.Add(ScriptConstants.AzureFunctionsHttpRouteDataKey, routeDataValues);
-            }
-
-            return function;
+            } 
         }
 
         protected override void OnInitializeConfig(ScriptHostConfiguration config)

test/WebJobs.Script.Tests/WebScriptHostManagerTests.cs

@@ -10,6 +10,8 @@
 using System.Net.Http;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
+using System.Web.Http;
+using System.Web.Http.Routing;
 using Microsoft.Azure.WebJobs.Host;
 using Microsoft.Azure.WebJobs.Script.Description;
 using Microsoft.Azure.WebJobs.Script.Tests;
@@ -194,6 +196,42 @@ public async Task OnTimeoutException_UsesToken_ManagerKeepsRunning()
             Assert.DoesNotContain(trace.Traces, t => t.Message == "A function timeout has occurred. Host is shutting down.");
         }
 
+        [Fact]
+        public void AddRouteDataToRequest_DoesNotAddRequestProperty_WhenRouteDataNull()
+        {
+            var mockRouteData = new Mock<IHttpRouteData>(MockBehavior.Strict);
+            IDictionary<string, object> values = null;
+            mockRouteData.Setup(p => p.Values).Returns(values);
+            HttpRequestMessage request = new HttpRequestMessage();
+
+            WebScriptHostManager.AddRouteDataToRequest(mockRouteData.Object, request);
+
+            Assert.False(request.Properties.ContainsKey(ScriptConstants.AzureFunctionsHttpRouteDataKey));
+        }
+
+        [Fact]
+        public void AddRouteDataToRequest_AddsRequestProperty_WhenRouteDataNotNull()
+        {
+            var mockRouteData = new Mock<IHttpRouteData>(MockBehavior.Strict);
+            IDictionary<string, object> values = new Dictionary<string, object>
+            {
+                { "p1", "abc" },
+                { "p2", 123 },
+                { "p3", null },
+                { "p4", RouteParameter.Optional }
+            };
+            mockRouteData.Setup(p => p.Values).Returns(values);
+            HttpRequestMessage request = new HttpRequestMessage();
+
+            WebScriptHostManager.AddRouteDataToRequest(mockRouteData.Object, request);
+
+            var result = (IDictionary<string, object>)request.Properties[ScriptConstants.AzureFunctionsHttpRouteDataKey];
+            Assert.Equal(result["p1"], "abc");
+            Assert.Equal(result["p2"], 123);
+            Assert.Equal(result["p3"], null);
+            Assert.Equal(result["p4"], null);
+        }
+
         private async Task RunTimeoutExceptionTest(TraceWriter trace, bool handleCancellation)
         {
             TimeSpan gracePeriod = TimeSpan.FromMilliseconds(5000);