Jackson JsonRootName doesn’t add any root value

I am serialising an object, which I’d like to put a root value for.

This is my class.

@JsonRootName(value = "user")
public class User {
    @JsonProperty
    private String name;
    @JsonProperty
    private int id;

    public User(int id, String name) {
        this.name = name;
        this.id = id;
    }
}

This is how I am serialising it:

 public static void main(String[] args) throws JsonProcessingException {
        User user = new User(1, "foobar");
        ObjectMapper mapper = new ObjectMapper();
        String serilizedValue = mapper.writeValueAsString(user);
        System.out.println(serilizedValue);
    }

But the serialised value is:

{"name":"foobar","id":1}

While I was hopping to have a root json value as fed in the class definition.

Could you help with that please?

Answer

@JsonRootName(value = "user")
public static class User {
        @JsonProperty
        private String name;
        @JsonProperty
        private int id;

        public User(int id, String name) {
            this.name = name;
            this.id = id;
        }
}

public static void main(String[] args) throws InterruptedException, ParseException, JsonProcessingException {
      User user = new User(1, "foobar");
      ObjectMapper mapper = new ObjectMapper();
      mapper.enable(SerializationFeature.WRAP_ROOT_VALUE);
      String serilizedValue = mapper.writeValueAsString(user);
      System.out.println(serilizedValue);
}

Output:

{"user":{"name":"foobar","id":1}}

You need to enable WRAP_ROOT_VALUE on the object mapper