Add support to get/set value of tag/property at any level

In previous implementation, there is a limitation in the Get/Set method of TwinExtension: only the value at top level could be get/set. In other words, Twin.Tags.Get("Location.City") is not supported (it will cause exception raised in SDK). In this code change, we are going to enable get/set at any level.

Common/Extensions/TwinCollectionExtension.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Newtonsoft.Json.Linq;
 
 namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extensions
@@ -21,6 +22,11 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extension
         /// <returns>Enumerator returns the flat name and value</returns>
         static public IEnumerable<KeyValuePair<string, TwinValue>> AsEnumerableFlatten(this TwinCollection collection, string prefix = "")
         {
+            if (collection == null)
+            {
+                throw new ArgumentNullException();
+            }
+
             foreach (KeyValuePair<string, object> pair in collection)
             {
                 if (pair.Value is TwinCollection)
@@ -47,12 +53,12 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extension
                         LastUpdated = (pair.Value as TwinCollectionValue)?.GetLastUpdated()
                     });
                 }
-#if DEBUG
                 else
                 {
+#if DEBUG
                     throw new ApplicationException($"Unexpected TwinCollection item type: {pair.Value.GetType().FullName} @ {prefix}{pair.Key}");
-                }
 #endif
+                }
             }
         }
 
@@ -76,12 +82,192 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extension
                         LastUpdated = (child.Value as TwinCollectionValue)?.GetLastUpdated()
                     });
                 }
-#if DEBUG
                 else
                 {
+#if DEBUG
                     throw new ApplicationException($"Unexpected TwinCollection item JTokenType: {child.Value.Type} @ {prefix}{child.Name}");
-                }
 #endif
+                }
+            }
+        }
+
+        /// <summary>
+        /// Get value of given tag or property specified by the flat name
+        /// </summary>
+        /// <param name="collection">Twin.Tag, Twin.Properties.Desired or Twin.Properties.Reported</param>
+        /// <param name="flatName">The flat name with prefix such as 'tags.' and so on</param>
+        /// <returns>The value in dynamic, or null in case error</returns>
+        static public dynamic Get(this TwinCollection collection, string flatName)
+        {
+            if (collection == null || string.IsNullOrWhiteSpace(flatName))
+            {
+                throw new ArgumentNullException();
+            }
+
+            return Get(collection, flatName.Split('.'));
+        }
+
+        static private dynamic Get(this TwinCollection collection, IEnumerable<string> names)
+        {
+            var name = names.First();
+
+            // Pick node on current level
+            if (!collection.Contains(name))
+            {
+                // No desired node found. Return null as error
+                return null;
+            }
+            var child = collection[name];
+
+            if (names.Count() == 1)
+            {
+                // Current node is the target node, , return the value
+                return child;
+            }
+            else if (child is TwinCollection)
+            {
+                // Current node is container, go to next level
+                return Get(child as TwinCollection, names.Skip(1));
+            }
+            else if (child is JContainer)
+            {
+                // Current node is container, go to next level
+                return Get(child as JContainer, names.Skip(1));
+            }
+            else
+            {
+                // Currently, the container could only be TwinCollection or JContainer
+#if DEBUG
+                throw new ApplicationException($"Unexpected TwinCollection item type: {child.GetType().FullName} @ ...{name}");
+#else
+                return null;
+#endif
+            }
+        }
+
+        static private dynamic Get(this JContainer container, IEnumerable<string> names)
+        {
+            var name = names.First();
+
+            // Pick node on current level
+            var child = container[name];
+            if (child == null)
+            {
+                // No desired node found. Return null as error
+                return null;
+            }
+
+            if (names.Count() == 1)
+            {
+                // Current node is the target node, return the value
+                return child;
+            }
+            else if (child is JContainer)
+            {
+                // Current node is container, go to next level
+                return Get(child as JContainer, names.Skip(1));
+            }
+            else
+            {
+                // The next level of JContainer must be JContainer
+#if DEBUG
+                throw new ApplicationException($"Unexpected TwinCollection item JTokenType: {child.Type} @ {child.Path}");
+#else
+                return null;
+#endif
+            }
+        }
+
+        /// <summary>
+        /// Add/Set value of given tag or property
+        /// Reminder: it is not allow to set value on the node has children
+        /// </summary>
+        /// <param name="collection">Twin.Tag, Twin.Properties.Desired or Twin.Properties.Reported</param>
+        /// <param name="flatName">The flat name with prefix such as 'tags.' and so on</param>
+        /// <param name="value">The value to be set</param>
+        static public void Set(this TwinCollection collection, string flatName, dynamic value)
+        {
+            if (collection == null || string.IsNullOrWhiteSpace(flatName))
+            {
+                throw new ArgumentNullException();
+            }
+
+            Set(collection, flatName.Split('.'), value);
+        }
+
+        static private void Set(this TwinCollection collection, IEnumerable<string> names, dynamic value)
+        {
+            var name = names.First();
+
+            if (names.Count() == 1)
+            {
+                // Current node is the target node, set the value
+                collection[name] = value;
+            }
+            else if (!collection.Contains(name))
+            {
+                // Current node is container, go to next level
+                // The target collection is not exist, create and add it
+                // Reminder: the 'add' operation perform 'copy' rather than 'link'
+                var newCollection = new TwinCollection();
+                Set(newCollection, names.Skip(1), value);
+                collection[name] = newCollection;
+            }
+            else
+            {
+                var child = collection[name];
+                if (child is TwinCollection)
+                {
+                    // The target collection is there. Go to next level
+                    Set(child as TwinCollection, names.Skip(1), value);
+                }
+                else if (child is JContainer)
+                {
+                    // The target collection is there. Go to next level
+                    Set(child as JContainer, names.Skip(1), value);
+                }
+                else
+                {
+                    // Currently, the container could only be TwinCollection or JContainer
+#if DEBUG
+                    throw new ApplicationException($"Unexpected TwinCollection item type: {child.GetType().FullName} @ ...{name}");
+#endif
+                }
+            }
+        }
+
+        static private void Set(this JContainer container, IEnumerable<string> names, dynamic value)
+        {
+            var name = names.First();
+
+            if (names.Count() == 1)
+            {
+                // Current node is the target node, set the value
+                container[name] = value;
+            }
+            else if (!container.Contains(name))
+            {
+                // The target container is not exist, create and add it
+                var newContainer = new JObject();
+                Set(newContainer, names.Skip(1), value);
+                container[name] = newContainer;
+                return;
+            }
+            else
+            {
+                // Current node is container, go to next level
+                var child = container[name];
+                if (child is JContainer)
+                {
+                    Set(child as JContainer, names.Skip(1), value);
+                }
+                else
+                {
+                    // The next level of JContainer must be JContainer
+#if DEBUG
+                    throw new ApplicationException($"Unexpected TwinCollection item JTokenType: {child.Type} @ {child.Path}");
+#endif
+                }
             }
         }
     }

Common/Extensions/TwinExtension.cs

@@ -39,7 +39,7 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extension
                 if (flatName.TryTrimPrefix(selector.Key, out name))
                 {
                     var collection = selector.Value(twin);
-                    return collection.Contains(name) ? collection[name] : null;
+                    return TwinCollectionExtension.Get(collection, name);
                 }
             }
 
@@ -68,7 +68,7 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.Common.Extension
             {
                 if (flatName.TryTrimPrefix(selector.Key, out name))
                 {
-                    selector.Value(twin)[name] = value;
+                    TwinCollectionExtension.Set(selector.Value(twin), name, value);
                     return;
                 }
             }

UnitTests/Common/TwinCollectionExtensionTests.cs

@@ -48,6 +48,49 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.UnitTests.Common
             Assert.Equal((string)tags[7].Value.Value.Value, "Device001");
         }
 
+        [Fact]
+        public void GetTest()
+        {
+            var twin = BuildRetrievedTwin();
+
+            Assert.Equal(twin.Tags.Get("DisplayName").ToString(), "Device001");
+            Assert.Equal(twin.Tags.Get("Location.City").ToString(), "Beijing");
+            Assert.Equal((double)twin.Tags.Get("LastTelemetry.Telemetry.Temperature"), 30.5);
+
+            Assert.Null(twin.Tags.Get("x"));
+            Assert.Throws<ArgumentNullException>(() => twin.Tags.Get(null));
+        }
+
+        [Fact]
+        public void SetTest()
+        {
+            var twin = BuildRetrievedTwin();
+
+            // Replace leaf
+            twin.Tags.Set("Location.City", "Shanghai");
+            Assert.Equal(twin.Tags.Get("Location.City").ToString(), "Shanghai");
+
+            // Add leaf (same level)
+            twin.Tags.Set("Location.Dummy", "n/a");
+            Assert.Equal(twin.Tags.Get("Location.Dummy").ToString(), "n/a");
+
+            // Add left (new level)
+            twin.Tags.Set("Location.City.Short", "SH");
+            Assert.Equal(twin.Tags.Get("Location.City.Short").ToString(), "SH");
+
+            // Replace intermedia node
+            twin.Tags.Set("LastTelemetry.Telemetry", 3);
+            Assert.Equal((int)twin.Tags.Get("LastTelemetry.Telemetry"), 3);
+
+            // Replace leaf
+            twin.Properties.Desired.Set("FirmwareVersion.Minor", 1);
+            Assert.Equal((int)twin.Properties.Desired.Get("FirmwareVersion.Minor"), 1);
+
+            // Replace intermedia node
+            twin.Properties.Desired.Set("FirmwareVersion.Build", 1002);
+            Assert.Equal((int)twin.Properties.Desired.Get("FirmwareVersion.Build"), 1002);
+        }
+
         private Twin BuildRetrievedTwin()
         {
             var twin = new Twin();
@@ -71,6 +114,16 @@ namespace Microsoft.Azure.Devices.Applications.RemoteMonitoring.UnitTests.Common
 
             twin.Tags["DisplayName"] = "Device001";
 
+            var build = new TwinCollection();
+            build["Year"] = 2016;
+            build["Month"] = 11;
+
+            var version = new TwinCollection();
+            version["Major"] = 3;
+            version["Minor"] = 0;
+            version["Build"] = build;
+            twin.Properties.Desired["FirmwareVersion"] = version;
+
             return JsonConvert.DeserializeObject<Twin>(twin.ToJson());
         }
     }