Avoid responding JSON field with particular value

Question

I'm using Jersey and Jackson to build a web application. Responses will be returned by using logic similar to the code snippets below. (unrelated parts are deleted)

public Response toResponse() {
    String name = // some methods to get name
    Integer score = // some methods to get score
    final MyDTO dto = new MyDTO(name, score);
    return Response
        .ok()
        .encoding(StandardCharsets.UTF_8.toString())
        .type(MediaType.APPLICATION_JSON_TYPE)
        .entity(dto)
        .build();
}

And the MyDTO class:

@XmlRootElement
public final class MyDTO {
    @NotNull final private String name;
    @NotNull final private Integer score;
    // constructor, getters, setters...
}

And I'm allowed to have only non-null values in MyDTO. What I want to achieve is to hide score field in the JSON response when the score exactly equals to 0. I looked into questions like here and here, but cannot manage to find a usable answer.

Example:
when John's score was 1: {"name": "John", "score": 1}
when John's score was 0: {"name": "John"}

what do you mean by hide? do you want to complete remove it or just set it as private? — Jonathan Portorreal, Feb 08 '17 at 06:17
@JonathanPortorreal complete remove the field from the JSON response — choasia, Feb 08 '17 at 06:39
i can't think of any clever way, but you could create another class that doesn't have the `score` field and use that one when necessary. — Jonathan Portorreal, Feb 08 '17 at 06:41
@JonathanPortorreal Thanks for you comment and yes, using another class can achieve this. But actually I have 3 fields need to meet this requirement, so I'm wondering if there's any better solutions rather than generating 4 different classes. — choasia, Feb 08 '17 at 06:45
I propose you to have all non-primitive types like Integer instead of int and use the @JsonInclude(Include.NON_NULL) annotation — Balakrishna Avulapati, Feb 08 '17 at 07:09
@BalakrishnaAvulapati Yeah, I think `@JsonInclude` will be a perfect option if it supports regular expression. — choasia, Feb 08 '17 at 07:27
@choasia : The NON_NULL "indicates that only properties with non-null values are to be included.", Seems like a sound proposal! https://fasterxml.github.io/jackson-annotations/javadoc/2.7/com/fasterxml/jackson/annotation/JsonInclude.Include.html#NON_NULL — Henrik Aasted Sørensen, Feb 08 '17 at 07:30
@BalakrishnaAvulapati: You should type that up as an answer. — Henrik Aasted Sørensen, Feb 08 '17 at 07:30
@choasia: Perhaps this http://www.baeldung.com/jackson-serialize-field-custom-criteria — Henrik Aasted Sørensen, Feb 10 '17 at 10:40
@Henrik this link is definitely useful. Although it is much more verbose, it is more flexible! — choasia, Feb 10 '17 at 13:46

score 2 · Accepted Answer · answered Feb 08 '17 at 11:04

2

use the answer by @Henrik changing the annotation to JsonInclude.Include.NON_DEFAULT. Hope this is what you are expecting

answered Feb 08 '17 at 11:04

Balakrishna Avulapati

231
2
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Although I cannot define the default value by myself, it did work for current requirement! Thanks a lot. – choasia Feb 09 '17 at 01:22

score 0 · Answer 2 · answered Feb 08 '17 at 08:15

0

Decided to try out @BalakrishnaAvulapati's proposal, and it definitely seems like the correct approach.

@JsonInclude(JsonInclude.Include.NON_NULL)
public static class Player {
    private String nick;
    private Integer score;

    // Omitting getter/setter for nick field

    public Integer getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score == 0 ? null : Integer.valueOf(score);
    }
}

answered Feb 08 '17 at 08:15

Henrik Aasted Sørensen

6,966
11
51
60

Hi, it is a great approach but it will cause some side effect since `MyDTO` is not supposed to have any field with null value. It's a simplified code snippet, I'm sorry that I didn't mention it in the question. I'd appreciate you if you could give an answer without setting it to null. – choasia Feb 08 '17 at 08:38
@choasia : Well, if I had another approach, I wouldn't have "stolen" this rather elegant one. :) – Henrik Aasted Sørensen Feb 08 '17 at 08:57
@choasia : But you might want to start researching creating your own, specialized serializer. – Henrik Aasted Sørensen Feb 08 '17 at 08:58
Yes, I'm looking into it. – choasia Feb 08 '17 at 09:03

Avoid responding JSON field with particular value

2 Answers2