MonthDaySerializer does not serialize objects into array

[XhstormR]

Unlike YearMonthSerializer serialize objects as array " [2018, 5]", MonthDaySerializer serialize to "--03-02"

I notice document say, what should i do :

NOTE: unlike many other date/time type serializers, this serializer will only use Array notation if explicitly instructed to do so with JsonFormat (either directly or through per-type defaults) and NOT with global defaults.

I use org.springframework.boot:spring-boot-starter-web:2.1.3.RELEASE,
com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.8,
com.fasterxml.jackson.module:jackson-module-kotlin:2.9.8

application.yml

  jackson:
    serialization:
      INDENT_OUTPUT: false
      WRITE_DATES_AS_TIMESTAMPS: true

[XhstormR]

I don't know how to make the MonthDaySerializer serialize an object into an array？

[cowtowncoder]

This belongs under jackson-modules-java8, since that's where serializer is defined, will move.

[cowtowncoder]

MonthDaySerializer outputs things as JSON array by default (looking at code), so I would need a reproduction of your issue. It could be due to framework you are using ignoring WRITE_DATES_AS_TIMESTAMPS setting.

[XhstormR]

Thanks, This is the smallest reproduction.

TEST1.zip

C:\Users\Leo>curl http://127.0.0.1:8080/t1
"--03-27"
C:\Users\Leo>curl http://127.0.0.1:8080/t2
[2019,3]
C:\Users\Leo>curl http://127.0.0.1:8080/t3
[2019,3,27,15,0,45,825499000]

[wilkinsona]

From the referenced Spring Boot issue, here's an even smaller reproduction:

ObjectMapper objectMapper = new ObjectMapper().enable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS).registerModule(new JavaTimeModule());
System.out.println(objectMapper.writeValueAsString(MonthDay.now()));
System.out.println(objectMapper.writeValueAsString(YearMonth.now()));
System.out.println(objectMapper.writeValueAsString(LocalDateTime.now()));

The above code will produce output similar to the following:

"--03-28"
[2019,3]
[2019,3,28,15,35,59,579000000]

[XhstormR]

Has anyone noticed here?

[cowtowncoder]

Ok finally got around to this one.

So: for some reason, original implementation defaulted to textual, not array-based, and since there is no way to distinguish "left as default" setting for use-timestamps from explicit, indication has to be done some other way.
There are 2 main mechanisms: annotation with @JsonFormat and "config overrides".

Former is

    static class Wrapper {
        @JsonFormat(shape = JsonFormat.Shape.ARRAY) // or NUMBER
        public MonthDay value;
    }

and config overrides something like

objectMapper.configOverride(MonthDay.class)
    .setFormat(JsonFormat.Value.forShape(JsonFormat.Shape.ARRAY);

Now: these work, but it seems that deserialization part does NOT actually work at this point.
So I'll leave the issue open for now. I will add tests for serialization for 2.9, but deserialization fix probably needs to go in 2.10.0.

[cowtowncoder]

Closing this, follow-up under #121.