DateTimeSerializerBase doesn't use WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS with java.sql.Timestamp

[hadrienk]

When converted using DateTimeSerializerBase, java.sql.Timestamp instances are not written in nanoseconds, even if the WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS feature is enabled.

I found this error doing the following:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
mapper.configure(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS, true);
mapper.configure(DeserializationFeature.READ_DATE_TIMESTAMPS_AS_NANOSECONDS, true);
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, true);
mapper.convertValue(new Timestamp(1456412409000), Instant.class)

[cowtowncoder]

@hadrienk Unfortunately timestamp resolution with pre-Java8 JDK types is limited to milliseconds, and as such this feature is only supported by Java 8 date/time types. This is mentioned in Javadocs.

[cowtowncoder]

Actually looking at javadocs for java.sql.Timestamp, it sounds like it could actually retain the additional part, so in theory perhaps this could be supportable.

The challenge here is that of choosing proper representation. Although in theory one could simply multiply value by 1 billion, this would likely cause problems with interoperability and/or backwards compatibility. It would seem preferable to either:

1. Use floating point number, so that milliseconds would be stored in integral part, and fractional part would define fraction of milliseconds.
2. Use a (JSON) Object with two properties
3. Use a 2-element array.

I can't remember how exactly Java 8 date/time module (https://github.com/FasterXML/jackson-modules-java8) handles this, but it would probably be worth checking it out for guidance.

[hadrienk]

Actually I should have written this bug in the java 8 data/time module.

[hadrienk]

I am closing it, feel free to reopen it is you think it is worth a fix :)

[cowtowncoder]

Actually this is the right place since java.sql.Timestamp is part of core JDK, not something added in Java 8.
Further I think it should be quite possible to add support as requested.

[cowtowncoder]

Rethinking this again since 2.9.0 release is looming. While it would be technically possible to add this, realized that there is no separate serializer for java.sql.Timestamp yet. And with usage of pre-Java8 datetime types going down addition for separate serializer is probably not worth the hassle.
So, closing.