Bug in subinterface query

src/Marten.Testing/Linq/query_with_inheritance.cs

@@ -142,5 +142,22 @@ public void get_all_subclasses_of_an_interface()
             theSession.Query<IPapaSmurf>().Count().ShouldBe(3);
         }
         // ENDSAMPLE
+
+        [Fact]
+        public void get_all_subclasses_of_an_interface_and_instantiate_them()
+        {
+            var smurf = new Smurf { Ability = "Follow the herd" };
+            var papa = new PapaSmurf { Ability = "Lead" };
+            var papy = new PapySmurf { Ability = "Lead" };
+            var brainy = new BrainySmurf { Ability = "Invent" };
+            theSession.Store(smurf, papa, brainy, papy);
+
+            theSession.SaveChanges();
+
+            var list = theSession.Query<IPapaSmurf>().ToList();
+            list.Count().ShouldBe(3);
+            list.Where(s => s.Ability == "Invent").Count().ShouldBe(1);
+        }
+
     }
 }

src/Marten/Schema/Hierarchies/SubClassDocumentStorage.cs

@@ -16,10 +16,12 @@ public class SubClassDocumentStorage<T, TBase>
         where TBase : class
     {
         private readonly IDocumentStorage _parent;
+        private readonly SubClassMapping _mapping;
 
-        public SubClassDocumentStorage(IDocumentStorage parent)
+        public SubClassDocumentStorage(IDocumentStorage parent, SubClassMapping mapping)
         {
             _parent = parent;
+            _mapping = mapping;
         }
 
         public Type DocumentType => typeof(T);
@@ -98,8 +100,11 @@ public T Resolve(int startingIndex, DbDataReader reader, IIdentityMap map)
             var id = reader[startingIndex + 1];
 
             var version = reader.GetFieldValue<Guid>(3);
+            var typeAlias = reader.GetString(startingIndex + 2);
 
-            return map.Get<TBase>(id, typeof(T), json, version) as T;
+            var actualType = _mapping.TypeFor(typeAlias);
+
+            return map.Get<TBase>(id, actualType, json, version) as T;
         }
 
         public async Task<T> ResolveAsync(int startingIndex, DbDataReader reader, IIdentityMap map,
@@ -109,8 +114,9 @@ public async Task<T> ResolveAsync(int startingIndex, DbDataReader reader, IIdent
             var id = await reader.GetFieldValueAsync<object>(startingIndex + 1, token).ConfigureAwait(false);
 
             var version = await reader.GetFieldValueAsync<Guid>(3, token).ConfigureAwait(false);
+            var typeAlias = await reader.GetFieldValueAsync<string>(startingIndex + 2, token).ConfigureAwait(false);
 
-            return map.Get<TBase>(id, typeof(T), json, version) as T;
+            return map.Get<TBase>(id, _mapping.TypeFor(typeAlias), json, version) as T;
         }
 
 

src/Marten/Schema/SubClassMapping.cs

@@ -114,7 +114,7 @@ private WhereFragment toBasicWhere()
         public IDocumentStorage BuildStorage(IDocumentSchema schema)
         {
             var parentStorage = Parent.As<IDocumentMapping>().BuildStorage(schema);
-            return typeof(SubClassDocumentStorage<,>).CloseAndBuildAs<IDocumentStorage>(parentStorage, DocumentType,
+            return typeof(SubClassDocumentStorage<,>).CloseAndBuildAs<IDocumentStorage>(parentStorage, this, DocumentType,
                 Parent.DocumentType);
         }
 
@@ -148,6 +148,11 @@ public IncludeJoin<TOther> JoinToInclude<TOther>(JoinType joinType, IQueryableDo
             return Parent.JoinToInclude(joinType, other, members, callback);
         }
 
+        public Type TypeFor(string alias)
+        {
+            return Parent.TypeFor(alias);
+        }
+
         private static string GetTypeMartenAlias(Type documentType)
         {
             return GetTypeMartenAlias(new MappedType(documentType));