The JSON value '/Date(-62135575200000-0600)/' could not be converted to System.DateTime about core HOT 6 CLOSED

@LeaFrock Try something like this:

		private static readonly JsonSerializerOptions s_ThingOptions = new()
		{
			Converters = { new JsonMicrosoftDateTimeWithOffsetConverter() }
		};

		public Thing ParseThingFromJson(string json)
		{
			return JsonSerializer.Deserialize<Thing>(json, s_ThingOptions);
		}

		public sealed class JsonMicrosoftDateTimeWithOffsetConverter : JsonConverterFactory
		{
			private readonly JsonMicrosoftDateTimeOffsetConverter _DateTimeOffsetFactory = new();

			public override bool CanConvert(Type typeToConvert) => typeToConvert == typeof(DateTime);

			public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)
			{
				return new Converter(
					(JsonConverter<DateTimeOffset>)_DateTimeOffsetFactory.CreateConverter(typeof(DateTimeOffset), options));
			}

			private class Converter : JsonConverter<DateTime>
			{
				private readonly JsonConverter<DateTimeOffset> _DateTimeOffsetConverter;

				public Converter(JsonConverter<DateTimeOffset> dateTimeOffsetConverter)
				{
					_DateTimeOffsetConverter = dateTimeOffsetConverter;
				}

				public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
				{
					DateTimeOffset dateTimeOffset = _DateTimeOffsetConverter.Read(ref reader, typeToConvert, options);
					return dateTimeOffset.LocalDateTime;
				}

				public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
					=> _DateTimeOffsetConverter.Write(writer, value, options);
			}
		}

What that will do is round-trip your values using local time.

If you read a value from the DB like \/Date(1580803200000-0500)\/ on a system in the pacific timezone and then immediately wrote it back, it would be changed to \/Date(1580803200000-0800)\/. The reason for that is DateTime can't store the offset. It either has to be UTC or Local.

If all your systems are in the same time zone, that should work fine. If your system are not, I recommend switching your ORM to DateTimeOffset because that is what it is for 😄 Sounds like the current design might be bugged.

from core.

@Malincoln9 Are you able to switch the target type to DateTimeOffset? The JsonMicrosoftDateTimeConverter doesn't understand the time offset in your JSON ("-0600") but JsonMicrosoftDateTimeOffsetConverter can handle that.

Example from the tests:

from core.

I was able to make that work. Would have liked to keep it DateTime, but thanks.

from core.

Same issue, but I cannot switch the target type to DateTimeOffset. The situation is that, the DateTime part of our some database entities is stored like /Date(...+..)/ in redis, but the class is defined by ORM as DateTime instead of DateTimeOffset(DBFirst). I have to be compatible with some old apps using redis too, and not affect ORM in order to avoid other problems.

Any workaround?

from core.

Spoke offline with @CodeBlanch who is going to create a PR against this issue.

After looking at the DataContractJson docs, we see that "/Date(700000+0500)/" is actually a DateTime format and not DateTimeOffset format. So JsonMicrosoftDateTimeConverter should be handling this case. If there is any +/- offset it's deserialized to local time; if not, it's deserialized to UTC

https://docs.microsoft.com/en-us/dotnet/framework/wcf/feature-details/stand-alone-json-serialization#datetime-wire-format

"The part that consists of "+0500" in the example is optional and indicates that the time is of the Local kind - that is, should be converted to the local time zone on deserialization. If it is absent, the time is deserialized as Utc. The actual number ("0500" in this example) and its sign (+ or -) are ignored."

from core.

3.0.0-beta2 has been published which updates JsonMicrosoftDateTimeConverter to follow the spec linked above.

from core.