MessagePack: Fix client serialization for multiple levels of inheritance

src/OpenRiaServices.Client.DomainClients.Http/Framework/MessagePack/Converters/ObjectConverterFactory.cs

@@ -49,17 +49,22 @@ public ObjectConverterFactory(IEnumerable<Type> entityTypes)
                 if (knownTypes.Count <= 1)
                     continue;
 
-                // Skip base types, it has KnownType attributes and is handled correctly
-                if (item.Key.BaseType == typeof(Entity))
-                    continue;
-
                 converters.Add(item.Key, (MessagePackConverter)Activator.CreateInstance(typeof(ObjectConverter<>).MakeGenericType(item.Key), [knownTypes])!);
             }
             converters.Add(typeof(object), new ObjectConverter<object>(allTypes));
 
             _converters = converters.ToFrozenDictionary();
         }
 
+        /// <summary>
+        /// Generate DerivedTypeUnion required for the ObjectConverterFactory to work.
+        /// </summary>
+        /// <remarks>
+        /// In order to prevent Nerdabank.MessagePack from creating additional discriminators we must disable the built in inheritance support for the types.
+        /// </remarks>
+        public IEnumerable<DerivedTypeUnion> GetDerivedTypeUnions()
+            => _converters.Keys.Select(DerivedTypeUnion.CreateDisabled);
+
         MessagePackConverter? IMessagePackConverterFactory.CreateConverter(Type type, ITypeShape? shape, in ConverterContext context)
         {
             // Only return type shapes for specified converter, this allows nerdbank default converters to be generated for other providers

src/OpenRiaServices.Client.DomainClients.Http/Framework/MessagePackHttpDomainClientFactory.cs

@@ -45,9 +45,11 @@ internal MessagePackSerializer GetSerializer(Type service, IEnumerable<Type> kno
         {
             return _serializerCache.GetOrAdd(service, static (_, args) =>
             {
+                var converterFactory = new ObjectConverterFactory(args.knownTypes);
                 return args.Item1.BaseSerializerSerializer with
                 {
-                    ConverterFactories = [new ObjectConverterFactory(args.knownTypes), .. args.Item1.BaseSerializerSerializer.ConverterFactories]
+                    ConverterFactories = [converterFactory, .. args.Item1.BaseSerializerSerializer.ConverterFactories],
+                    DerivedTypeUnions = [..converterFactory.GetDerivedTypeUnions(), .. args.Item1.BaseSerializerSerializer.DerivedTypeUnions]
                 };
 
             }, (this, knownTypes));

src/Test/OpenRiaservices.EndToEnd.Wcf.Test/Data/InheritanceTests.cs

@@ -5,12 +5,10 @@
 using System.Globalization;
 using System.Linq;
 using System.Reflection;
+using System.Threading.Tasks;
 using Cities;
 using Microsoft.Silverlight.Testing;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using OpenRiaServices.Silverlight.Testing;
-using TestDomainServices;
-using TestDomainServices.NamedUpdates;
 
 namespace OpenRiaServices.Client.Test
 {
@@ -394,6 +392,27 @@ public void Inherit_Run_Call_Derived_Custom_Method_On_Abstract_Base_()
             EnqueueTestComplete();
         }
 
+        [TestMethod]
+        [Description("Ensure querying works for 3 levels of inheritance")]
+        public async Task Inherit_Queries()
+        {
+            // Inheritance is City <-- CityWithEditHistory <-- CityWithInfo
+            // Ensure we can methods retrieve entities at all levels of the hierarchy
+            CityDomainContext baseContext = new CityDomainContext();
+            CityDomainContext middleContext = new CityDomainContext();
+            CityDomainContext mostDerivedContext = new CityDomainContext();
+
+            var baseResult = await baseContext.LoadAsync(baseContext.GetCitiesQuery());
+            var editResult = await middleContext.LoadAsync(middleContext.GetCitiesWithEditHistoryQuery());
+            var mostDerivedResult = await mostDerivedContext.LoadAsync(mostDerivedContext.GetCitiesWithInfoQuery());
+
+            // CityWithEditHistory is abstract so should be return exactly the same number of entities as CityWithInfo
+            Assert.HasCount(2, mostDerivedResult.Entities);
+            Assert.HasCount(2, editResult.Entities);
+            Assert.HasCount(2, baseResult.Entities.OfType<CityWithInfo>());
+            Assert.HasCount(11, baseResult.Entities);
+        }
+
         #endregion //Custom methods
 
         #region CUD