Add struct support to dapper

Dapper/SqlMapper.cs

@@ -926,10 +926,14 @@ private static CacheInfo GetCacheInfo(Identity identity)
             }
 #endif
 
-            if (type.IsClass && type != typeof(string) && type != typeof(byte[]) && type != typeof(System.Data.Linq.Binary))
+            if (
+                (type.IsClass && type != typeof(string) && type != typeof(byte[]) && type != typeof(System.Data.Linq.Binary)) ||
+                (type.IsValueType && !type.IsPrimitive && !(type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>)))
+                )
             {
-                return GetClassDeserializer(type, reader, startBound, length, returnNullIfFirstMissing);
+                return GetTypeDeserializer(type, reader, startBound, length, returnNullIfFirstMissing);
             }
+            
             return GetStructDeserializer(type, startBound);
 
         }
@@ -1437,7 +1441,7 @@ static List<FieldInfo> GetSettableFields(Type t)
         /// <param name="length"></param>
         /// <param name="returnNullIfFirstMissing"></param>
         /// <returns></returns>
-        public static Func<IDataReader, object> GetClassDeserializer(
+        public static Func<IDataReader, object> GetTypeDeserializer(
 #if CSHARP30
             Type type, IDataReader reader, int startBound, int length, bool returnNullIfFirstMissing
 #else
@@ -1445,11 +1449,11 @@ static List<FieldInfo> GetSettableFields(Type t)
 #endif
 )
         {
-            var dm = new DynamicMethod(string.Format("Deserialize{0}", Guid.NewGuid()), type, new[] { typeof(IDataReader) }, true);
+            var dm = new DynamicMethod(string.Format("Deserialize{0}", Guid.NewGuid()), type.IsValueType ? typeof(object) : type, new[] { typeof(IDataReader) }, true);
 
             var il = dm.GetILGenerator();
             il.DeclareLocal(typeof(int));
-            il.DeclareLocal(type);
+            var emptyLocal = il.DeclareLocal(type);
             bool haveEnumLocal = false;
             il.Emit(OpCodes.Ldc_I4_0);
             il.Emit(OpCodes.Stloc_0);
@@ -1485,7 +1489,20 @@ static List<FieldInfo> GetSettableFields(Type t)
 
             il.BeginExceptionBlock();
             // stack is empty
-            il.Emit(OpCodes.Newobj, type.GetConstructor(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, Type.EmptyTypes, null)); // stack is now [target]
+
+            if (type.IsValueType)
+            {
+                il.Emit(OpCodes.Ldloca, emptyLocal);
+                il.Emit(OpCodes.Initobj, type);
+                il.Emit(OpCodes.Ldloca, emptyLocal);
+            }
+            else
+            {
+                il.Emit(OpCodes.Newobj, type.GetConstructor(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, Type.EmptyTypes, null)); 
+            }
+
+            // stack is now [target]
+
             bool first = true;
             var allDone = il.DefineLabel();
             foreach (var item in setters)
@@ -1502,7 +1519,6 @@ static List<FieldInfo> GetSettableFields(Type t)
                     il.Emit(OpCodes.Stloc_0);// stack is now [target][target][reader][index]
                     il.Emit(OpCodes.Callvirt, getItem); // stack is now [target][target][value-as-object]
 
-
                     Type memberType = item.Property != null ? item.Property.Type : item.Field.FieldType;
 
                     if (memberType == typeof(char) || memberType == typeof(char?))
@@ -1579,9 +1595,16 @@ static List<FieldInfo> GetSettableFields(Type t)
                         }
                     }
                     if (item.Property != null)
+                    {
+                        if (type.IsValueType)
+                        {
+                            il.Emit(OpCodes.Call, item.Property.Setter); // stack is now [target]
+                        }
+                        else
                         {
                             il.Emit(OpCodes.Callvirt, item.Property.Setter); // stack is now [target]
                         }
+                    }
                     else
                     {
                         il.Emit(OpCodes.Stfld, item.Field); // stack is now [target]
@@ -1607,7 +1630,14 @@ static List<FieldInfo> GetSettableFields(Type t)
                 first = false;
                 index += 1;
             }
+            if (type.IsValueType)
+            {
+                il.Emit(OpCodes.Pop);
+            }
+            else
+            {
                 il.Emit(OpCodes.Stloc_1); // stack is empty
+            }
             il.MarkLabel(allDone);
             il.BeginCatchBlock(typeof(Exception)); // stack is Exception
             il.Emit(OpCodes.Ldloc_0); // stack is Exception, index
@@ -1617,7 +1647,16 @@ static List<FieldInfo> GetSettableFields(Type t)
             il.Emit(OpCodes.Stloc_1); // to make it verifiable
             il.EndExceptionBlock();
 
-            il.Emit(OpCodes.Ldloc_1); // stack is empty
+           
+            if (type.IsValueType)
+            {
+                il.Emit(OpCodes.Ldloc, emptyLocal); // stack is [rval]
+                il.Emit(OpCodes.Box, type);
+            }
+            else 
+            {
+                il.Emit(OpCodes.Ldloc_1); // stack is [rval]
+            }
             il.Emit(OpCodes.Ret);
 
             return (Func<IDataReader, object>)dm.CreateDelegate(typeof(Func<IDataReader,object>));

Tests/Tests.cs

@@ -16,6 +16,28 @@ class Tests
     {
         SqlConnection connection = Program.GetOpenConnection();
 
+        struct Car
+        {
+            public enum TrapEnum : int
+            {
+                A = 1,
+                B = 2
+            }
+            public string Name;
+            public int Age { get; set; }
+            public TrapEnum Trap { get; set; }
+        
+        }
+
+        public void TestStructs()
+        {
+            var car = connection.Query<Car>("select 'Ford' Name, 21 Age, 2 Trap").First();
+
+            car.Age.IsEqualTo(21);
+            car.Name.IsEqualTo("Ford");
+            ((int)car.Trap).IsEqualTo(2);
+        }
+
         public void SelectListInt()
         {
             connection.Query<int>("select 1 union all select 2 union all select 3")
@@ -1111,5 +1133,6 @@ public void TestAppendingAList()
             result[1].IsEqualTo(2);
             result[2].IsEqualTo(3);
         }
+
     }
 }