Chore/datetime kind

src/Parquet.Test/Serialisation/SchemaReflectorTest.cs

@@ -23,7 +23,7 @@
 
             public int[]? IntArray { get; set; }
 
             public bool MarkerField;
         }
 
         [Fact]
@@ -323,8 +323,11 @@
             [ParquetTimestamp]
             public DateTime TimestampDate { get; set; }
 
+            [ParquetTimestamp(useLogicalTimestamp: true, isAdjustedToUTC: false)]
+            public DateTime LogicalLocalTimestampDate { get; set; }
+
             [ParquetTimestamp(useLogicalTimestamp: true)]
-            public DateTime LogicalTimestampDate { get; set; }
+            public DateTime LogicalUtcTimestampDate { get; set; }
 
             [ParquetTimestamp]
             public DateTime? NullableTimestampDate { get; set; }
@@ -387,11 +390,22 @@
         }
 
         [Fact]
-        public void Type_DateTime_LogicalTimestamp() {
+        public void Type_DateTime_LogicalLocalTimestamp() {
+            ParquetSchema s = typeof(DatesPoco).GetParquetSchema(true);
+
+            DataField df = s.FindDataField(nameof(DatesPoco.LogicalLocalTimestampDate));
+            Assert.True(df is DateTimeDataField);
+            Assert.False(((DateTimeDataField)df).IsAdjustedToUTC);
+            Assert.Equal(DateTimeFormat.Timestamp, ((DateTimeDataField)df).DateTimeFormat);
+        }
+
+        [Fact]
+        public void Type_DateTime_LogicalUtcTimestamp() {
             ParquetSchema s = typeof(DatesPoco).GetParquetSchema(true);
 
-            DataField df = s.FindDataField(nameof(DatesPoco.LogicalTimestampDate));
+            DataField df = s.FindDataField(nameof(DatesPoco.LogicalUtcTimestampDate));
             Assert.True(df is DateTimeDataField);
+            Assert.True(((DateTimeDataField)df).IsAdjustedToUTC);
             Assert.Equal(DateTimeFormat.Timestamp, ((DateTimeDataField)df).DateTimeFormat);
         }
 

src/Parquet.Test/Types/LogicalTimestampTest.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using Parquet.Serialization;
+using Parquet.Serialization.Attributes;
+using Xunit;
+
+namespace Parquet.Test.Types {
+    public class LogicalTimestampTest {
+        internal class V1 {
+            public DateTime DateTimeUtc { get; set; }
+
+            public DateTime DateTimeLocal { get; set; }
+        }
+
+        internal class V2 {
+            [ParquetTimestamp(useLogicalTimestamp: true, isAdjustedToUTC: true)]
+
+            public DateTime DateTimeUtc { get; set; }
+
+            [ParquetTimestamp(useLogicalTimestamp: true, isAdjustedToUTC: false)]
+            public DateTime DateTimeLocal { get; set; }
+        }
+
+        [Fact]
+        public async Task SerializeDeserializeV1() {
+            var utc = new DateTime(2006, 1, 2, 15, 4, 5, DateTimeKind.Utc);
+            // TODO: should this be unspecified?
+            var local = new DateTime(2006, 1, 2, 15, 4, 5, DateTimeKind.Local);
+
+            var expected = new V1 {
+                DateTimeUtc = utc,
+                DateTimeLocal = local,
+            };
+
+            using var ms = new MemoryStream();
+            await ParquetSerializer.SerializeAsync([expected], ms);
+
+            ms.Position = 0;
+            IList<V1> actuals = await ParquetSerializer.DeserializeAsync<V1>(ms);
+            Assert.Single(actuals);
+            V1 actual = actuals.First();
+            Assert.Equal(utc, actual.DateTimeUtc);
+            Assert.Equal(DateTimeKind.Utc, actual.DateTimeUtc.Kind);
+            // Kind is changed from Local to UTC
+            Assert.Equal(local, actual.DateTimeUtc);
+            Assert.Equal(DateTimeKind.Utc, actual.DateTimeUtc.Kind);
+        }
+
+        [Fact]
+        public async Task SerializeDeserializeLogicalTimestamp() {
+            var utc = new DateTime(2006, 1, 2, 15, 4, 5, DateTimeKind.Utc);
+            // TODO: should this be unspecified?
+            var local = new DateTime(2006, 1, 2, 15, 4, 5, DateTimeKind.Local);
+
+            var expected = new V2 {
+                DateTimeUtc = utc,
+                DateTimeLocal = local,
+            };
+
+            using var ms = new MemoryStream();
+            await ParquetSerializer.SerializeAsync([expected], ms);
+
+            ms.Position = 0;
+            IList<V2> actuals = await ParquetSerializer.DeserializeAsync<V2>(ms);
+            Assert.Single(actuals);
+            V2 actual = actuals.First();
+            Assert.Equal(utc, actual.DateTimeUtc);
+            Assert.Equal(DateTimeKind.Utc, actual.DateTimeUtc.Kind);
+            Assert.Equal(local, actual.DateTimeLocal);
+            Assert.Equal(DateTimeKind.Local, actual.DateTimeLocal.Kind);
+        }
+    }
+}

src/Parquet/Serialization/Attributes/ParquetTimestampAttribute.cs

@@ -35,9 +35,11 @@ public class ParquetTimestampAttribute : Attribute {
         /// </summary>
         /// <param name="resolution"></param>
         /// <param name="useLogicalTimestamp"></param>
-        public ParquetTimestampAttribute(ParquetTimestampResolution resolution = ParquetTimestampResolution.Milliseconds, bool useLogicalTimestamp = false) {
+        /// <param name="isAdjustedToUTC"></param>
+        public ParquetTimestampAttribute(ParquetTimestampResolution resolution = ParquetTimestampResolution.Milliseconds, bool useLogicalTimestamp = false, bool isAdjustedToUTC = true) {
             Resolution = resolution;
             UseLogicalTimestamp = useLogicalTimestamp;
+            IsAdjustedToUTC = isAdjustedToUTC;
         }
 
         /// <summary>