Serialize UTC DateTime as Zulu-Time (#339)

Author: Tassilo Singhammer

src/Types.Tests/Types/DateTimeTypeTests.cs

@@ -7,13 +7,13 @@ namespace HotChocolate.Types
     public class DateTimeTypeTests
     {
         [Fact]
-        public void Serialize_DateTime()
+        public void Serialize_Utc_DateTime()
         {
             // arrange
             DateTimeType dateTimeType = new DateTimeType();
             DateTime dateTime = new DateTime(
                 2018, 6, 11, 8, 46, 14, DateTimeKind.Utc);
-            string expectedValue = "2018-06-11T08:46:14+00:00";
+            string expectedValue = "2018-06-11T08:46:14.000Z";
 
             // act
             string serializedValue = (string)dateTimeType.Serialize(dateTime);
@@ -30,7 +30,7 @@ public void Serialize_DateTimeOffset()
             DateTimeOffset dateTime = new DateTimeOffset(
                 new DateTime(2018, 6, 11, 8, 46, 14),
                 new TimeSpan(4, 0, 0));
-            string expectedValue = "2018-06-11T08:46:14+04:00";
+            string expectedValue = "2018-06-11T08:46:14.000+04:00";
 
             // act
             string serializedValue = (string)dateTimeType.Serialize(dateTime);
@@ -94,11 +94,59 @@ public void Deserialize_IsoString_DateTimeOffset()
                 new TimeSpan(4, 0, 0));
 
             // act
-            DateTimeOffset serializedValue = (DateTimeOffset)dateTimeType
+            DateTimeOffset deserializedValue = (DateTimeOffset)dateTimeType
                 .Deserialize("2018-06-11T08:46:14+04:00");
 
             // assert
-            Assert.Equal(dateTime, serializedValue);
+            Assert.Equal(dateTime, deserializedValue);
+        }
+
+        [Fact]
+        public void Deserialize_ZuluString_DateTimeOffset()
+        {
+            // arrange
+            DateTimeType dateTimeType = new DateTimeType();
+            DateTimeOffset dateTime = new DateTimeOffset(
+                new DateTime(2018, 6, 11, 8, 46, 14),
+                new TimeSpan(0, 0, 0));
+
+            // act
+            DateTimeOffset deserializedValue = (DateTimeOffset)dateTimeType
+                .Deserialize("2018-06-11T08:46:14.000Z");
+
+            // assert
+            Assert.Equal(dateTime, deserializedValue);
+        }
+
+        [Fact]
+        public void Deserialize_IsoString_DateTime()
+        {
+            // arrange
+            DateTimeType dateTimeType = new DateTimeType();
+            DateTime dateTime = new DateTime(2018, 6, 11, 8, 46, 14, DateTimeKind.Unspecified);
+
+            // act
+            DateTime deserializedValue = ((DateTimeOffset)dateTimeType
+                .Deserialize("2018-06-11T08:46:14+04:00")).DateTime;
+
+            // assert
+            Assert.Equal(dateTime, deserializedValue);
+            Assert.Equal(DateTimeKind.Unspecified, deserializedValue.Kind);
+        }
+
+        [Fact]
+        public void Deserialize_ZuluString_DateTime()
+        {
+            // arrange
+            DateTimeType dateTimeType = new DateTimeType();
+            DateTimeOffset dateTime = new DateTime(2018, 6, 11, 8, 46, 14, DateTimeKind.Utc);
+
+            // act
+            DateTime deserializedValue = ((DateTimeOffset)dateTimeType
+                .Deserialize("2018-06-11T08:46:14.000Z")).DateTime;
+
+            // assert
+            Assert.Equal(dateTime, deserializedValue);
         }
 
         [Fact]
@@ -123,7 +171,7 @@ public void ParseValue_DateTimeOffset()
             DateTimeOffset dateTime = new DateTimeOffset(
                 new DateTime(2018, 6, 11, 8, 46, 14),
                 new TimeSpan(4, 0, 0));
-            string expectedLiteralValue = "2018-06-11T08:46:14+04:00";
+            string expectedLiteralValue = "2018-06-11T08:46:14.000+04:00";
 
             // act
             StringValueNode stringLiteral =
@@ -134,13 +182,53 @@ public void ParseValue_DateTimeOffset()
         }
 
         [Fact]
-        public void ParseValue_DateTime()
+        public void ParseValue_Unspecified_DateTime()
+        {
+            // arrange
+            DateTimeType dateTimeType = new DateTimeType();
+            DateTime dateTime =
+                new DateTime(2018, 6, 11, 8, 46, 14, DateTimeKind.Unspecified);
+            DateTimeOffset offset = dateTime;
+            DateTime offsetDateTime = offset.DateTime;
+
+            // act
+            StringValueNode stringLiteral =
+                (StringValueNode)dateTimeType.ParseValue(dateTime);
+            StringValueNode stringLiteralOffset =
+                (StringValueNode)dateTimeType.ParseValue(offsetDateTime);
+
+            // assert
+            Assert.Equal(stringLiteralOffset, stringLiteral);
+        }
+
+        [Fact]
+        public void ParseValue_Local_DateTime()
+        {
+            // arrange
+            DateTimeType dateTimeType = new DateTimeType();
+            DateTime dateTime =
+                new DateTime(2018, 6, 11, 8, 46, 14, DateTimeKind.Local);
+            DateTimeOffset offset = dateTime;
+            DateTime offsetDateTime = offset.DateTime;
+
+            // act
+            StringValueNode stringLiteral =
+                (StringValueNode)dateTimeType.ParseValue(dateTime);
+            StringValueNode stringLiteralOffset =
+                (StringValueNode)dateTimeType.ParseValue(offsetDateTime);
+
+            // assert
+            Assert.Equal(stringLiteral, stringLiteralOffset);
+        }
+
+        [Fact]
+        public void ParseValue_Utc_DateTime()
         {
             // arrange
             DateTimeType dateTimeType = new DateTimeType();
             DateTime dateTime =
                 new DateTime(2018, 6, 11, 8, 46, 14, DateTimeKind.Utc);
-            string expectedLiteralValue = "2018-06-11T08:46:14+00:00";
+            string expectedLiteralValue = "2018-06-11T08:46:14.000Z";
 
             // act
             StringValueNode stringLiteral =

src/Types/Types/Scalars/DateTimeType.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using HotChocolate.Language;
 
 namespace HotChocolate.Types
@@ -18,17 +19,36 @@ public DateTimeType()
 
         protected override string Serialize(DateTime value)
         {
-            return value.ToString("yyyy-MM-ddTHH\\:mm\\:sszzz");
+            if (value.Kind == DateTimeKind.Utc)
+            {
+                return value.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffZ");
+            }
+
+            return value.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffzzz");
         }
 
         protected override string Serialize(DateTimeOffset value)
         {
-            return value.ToString("yyyy-MM-ddTHH\\:mm\\:sszzz");
+            if (value.Offset == TimeSpan.Zero)
+            {
+                return value.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffZ");
+            }
+
+            return value.ToString("yyyy-MM-ddTHH\\:mm\\:ss.fffzzz");
         }
 
         protected override bool TryParseLiteral(
             StringValueNode literal, out object obj)
         {
+            if (literal.Value != null && literal.Value.EndsWith("Z"))
+            {
+                if (DateTime.TryParse(literal.Value, null as IFormatProvider, DateTimeStyles.AssumeUniversal, out DateTime zDateTime))
+                {
+                    obj = new DateTimeOffset(zDateTime);
+                    return true;
+                }
+            }
+
             if (DateTimeOffset.TryParse(literal.Value, out DateTimeOffset dateTime))
             {
                 obj = dateTime;