`LocalDateTime` serialization issue with custom-configured `LocalDateTimeSerializer`

[mklinkj]

Hello.

There was no problem specifying the date format up to version 2.15.3, but it seems like it’s not applied in version 2.16.0

Example Project (v2.15.3)

• https://github.com/mklinkj/QnA/tree/master/Jackson/jackson-local-datetime-example

Example Project Zip File (v2.15.3)

• jackson-local-datetime-example.zip

Where to change version

• https://github.com/mklinkj/QnA/blob/f488d3f3ca2ceb3b7614902545c257e9b9f06df7/Jackson/jackson-local-datetime-example/gradle.properties#L5

ObjectMapper Setting

    ObjectMapper mapper =
        new ObjectMapper()
            .registerModule(
                new JavaTimeModule()
                    .addSerializer(
                        LocalDateTime.class,
                        new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("MM/dd/yyyy"))));

Run in Jackson 2.15.3

$ gradlew clean run

> Task :run
memberJson: {"name":"user00","registerDate":"12/25/2023"}

BUILD SUCCESSFUL in 2s
5 actionable tasks: 5 executed
$ 

Run in Jackson 2.16.0

$ gradlew clean run

> Task :run
memberJson: {"name":"user00","registerDate":[2023,12,25,1,2,3]}

BUILD SUCCESSFUL in 2s
5 actionable tasks: 5 executed
$ 

• ✨ The date format set in LocalDateTimeSerializer is not applied in the 2.16.0

I think it might be due to my incorrect settings… Anyway, I’ve shared it

Thank you, Have a nice day 👍

[cowtowncoder]

Ok, first of all: thank you for reporting this issue.

Second of all: I would highly recommend NOT constructing (de)serializers directly but letting JavaTimeModule do that; you can still apply pattern overrides with:

mapper.configOverride(LocalDateTime.class)
   .setFormat(JsonFormat.Value.forPattern(""MM/dd/yyyy""))

But be that as it may, the way you do things should also work.

[mklinkj]

@cowtowncoder

Hello.

I replaced the code as you replied above and confirmed that it works fine.

• commit
  • f2c3a58773562afcc1a040cf8910208aaaa359f0

Thanks. Have a nice day. 👍

[cowtowncoder]

@mklinkj Great!

I will still see if I can resolve the problem itself, but I am glad you were able to work around that.

[cowtowncoder]

Ok, I can see why this happens: 2.16 changed registration of (de)serializers in a way that would ignore anything added via JavaTimeModule.addXxx() methods -- this was not meant to be a way to add (de)serializers.

I'll have to think of how to change this; it should be doable, just not trivially simple.

[cowtowncoder]

Was quite simple in the end, fixed for 2.16.1. I assume there will be other reports for other custom registrations.

[cowtowncoder]

And there is at least #293.