Support enums (and nullable enums) in Query<T>, and check (extra tests) that...

Support enums (and nullable enums) in Query<T>, and check (extra tests) that they work fine for regular T with an enum / nullable-enum member

Dapper/SqlMapper.cs

@@ -929,12 +929,13 @@ private static CacheInfo GetCacheInfo(Identity identity)
                 return GetDynamicDeserializer(reader, startBound, length, returnNullIfFirstMissing);
             }
 #endif
-
-            if (!(typeMap.ContainsKey(type) || type.FullName == LinqBinary))
+            Type underlyingType = null;
+            if (!(typeMap.ContainsKey(type) || type.IsEnum || type.FullName == LinqBinary ||
+                (type.IsValueType && (underlyingType = Nullable.GetUnderlyingType(type)) != null && underlyingType.IsEnum)))
             {
                 return GetTypeDeserializer(type, reader, startBound, length, returnNullIfFirstMissing);
             }
-            return GetStructDeserializer(type, startBound);
+            return GetStructDeserializer(type, underlyingType ?? type, startBound);
 
         }
 #if !CSHARP30
@@ -1395,7 +1396,7 @@ private static int ExecuteCommand(IDbConnection cnn, IDbTransaction transaction,
             }
         }
 
-        private static Func<IDataReader, object> GetStructDeserializer(Type type, int index)
+        private static Func<IDataReader, object> GetStructDeserializer(Type type, Type effectiveType, int index)
         {
             // no point using special per-type handling here; it boils down to the same, plus not all are supported anyway (see: SqlDataReader.GetChar - not supported!)
 #pragma warning disable 618
@@ -1412,6 +1413,15 @@ private static int ExecuteCommand(IDbConnection cnn, IDbTransaction transaction,
                 return r => Activator.CreateInstance(type, r.GetValue(index));
             }
 #pragma warning restore 618
+
+            if (effectiveType.IsEnum)
+            {   // assume the value is returned as the correct type (int/byte/etc), but box back to the typed enum
+                return r =>
+                {
+                    var val = r.GetValue(index);
+                    return val is DBNull ? null : Enum.ToObject(effectiveType, val);
+                };
+            }
             return r =>
             {
                 var val = r.GetValue(index);

Tests/Tests.cs

@@ -1378,10 +1378,9 @@ public void TestInt16Usage()
             connection.Query<short?>("select cast(42 as smallint)").Single().IsEqualTo((short?)42);
             connection.Query<short?>("select cast(null as smallint)").Single().IsEqualTo((short?)null);
 
-            // hmmm.... these don't work currently... adding TODO
-            //connection.Query<ShortEnum>("select cast(42 as smallint)").Single().IsEqualTo((ShortEnum)42);
-            //connection.Query<ShortEnum?>("select cast(42 as smallint)").Single().IsEqualTo((ShortEnum?)42);
-            //connection.Query<ShortEnum?>("select cast(null as smallint)").Single().IsEqualTo((ShortEnum?)null);
+            connection.Query<ShortEnum>("select cast(42 as smallint)").Single().IsEqualTo((ShortEnum)42);
+            connection.Query<ShortEnum?>("select cast(42 as smallint)").Single().IsEqualTo((ShortEnum?)42);
+            connection.Query<ShortEnum?>("select cast(null as smallint)").Single().IsEqualTo((ShortEnum?)null);
 
             var row =
                 connection.Query<WithInt16Values>(
@@ -1401,7 +1400,34 @@ public void TestInt16Usage()
             row.NonNullableInt16Enum.IsEqualTo(ShortEnum.Six);
             row.NullableInt16Enum.IsEqualTo((ShortEnum?)null);
         }
+        public void TestInt32Usage()
+        {
+            connection.Query<int>("select cast(42 as int)").Single().IsEqualTo((int)42);
+            connection.Query<int?>("select cast(42 as int)").Single().IsEqualTo((int?)42);
+            connection.Query<int?>("select cast(null as int)").Single().IsEqualTo((int?)null);
+
+            connection.Query<IntEnum>("select cast(42 as int)").Single().IsEqualTo((IntEnum)42);
+            connection.Query<IntEnum?>("select cast(42 as int)").Single().IsEqualTo((IntEnum?)42);
+            connection.Query<IntEnum?>("select cast(null as int)").Single().IsEqualTo((IntEnum?)null);
 
+            var row =
+                connection.Query<WithInt32Values>(
+                    "select cast(1 as int) as NonNullableInt32, cast(2 as int) as NullableInt32, cast(3 as int) as NonNullableInt32Enum, cast(4 as int) as NullableInt32Enum")
+                    .Single();
+            row.NonNullableInt32.IsEqualTo((int)1);
+            row.NullableInt32.IsEqualTo((int)2);
+            row.NonNullableInt32Enum.IsEqualTo(IntEnum.Three);
+            row.NullableInt32Enum.IsEqualTo(IntEnum.Four);
+
+            row =
+    connection.Query<WithInt32Values>(
+        "select cast(5 as int) as NonNullableInt32, cast(null as int) as NullableInt32, cast(6 as int) as NonNullableInt32Enum, cast(null as int) as NullableInt32Enum")
+        .Single();
+            row.NonNullableInt32.IsEqualTo((int)5);
+            row.NullableInt32.IsEqualTo((int?)null);
+            row.NonNullableInt32Enum.IsEqualTo(IntEnum.Six);
+            row.NullableInt32Enum.IsEqualTo((IntEnum?)null);
+        }
 
         public class WithInt16Values
         {
@@ -1409,12 +1435,22 @@ public class WithInt16Values
             public short? NullableInt16 { get; set; }
             public ShortEnum NonNullableInt16Enum { get; set; }
             public ShortEnum? NullableInt16Enum { get; set; }
-
         }
         public enum ShortEnum : short
         {
             Zero = 0, One = 1, Two = 2, Three = 3, Four = 4, Five = 5, Six = 6
         }
+        public class WithInt32Values
+        {
+            public int NonNullableInt32 { get; set; }
+            public int? NullableInt32 { get; set; }
+            public IntEnum NonNullableInt32Enum { get; set; }
+            public IntEnum? NullableInt32Enum { get; set; }
+        }
+        public enum IntEnum : int
+        {
+            Zero = 0, One = 1, Two = 2, Three = 3, Four = 4, Five = 5, Six = 6
+        }
 
         public void TestTransactionCommit()
         {