Jackson ignore serialization of top-level field if all its nested fields are null

Question

I am using Jackson ObjectMapper to serialize a POJO. I have nested fields in the POJO. Eg: serializing class MyClass

public class MyClass {
    private A a;
    private int i;
    //getters and setters
}

public class A {
    private String s;
    //getters and setters
}

I want that if String s is null, the entire property A does not get serialized. That is, if String s is null, I want the output to be: {"myClass":{"i":10}}

But I am getting {"myClass":{"A":{},"i":10}} as the output instead.

I have set NON_EMPTY for serialization inclusion (mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY)), but it doesn't solve the problem

Possible duplicate of [How to tell Jackson to ignore a field during serialization if its value is null?](http://stackoverflow.com/questions/11757487/how-to-tell-jackson-to-ignore-a-field-during-serialization-if-its-value-is-null) — Arpit Aggarwal, Mar 06 '17 at 17:00
I don't think this question is a duplicate because it regards nested objects. The referred question does not handle it, and the solution there does not suffice. — Stempler, Apr 10 '19 at 08:23

freedev · Answer 1 · 2017-03-06T10:42:21.547

1

AFAIK you cannot do this with standard annotations, but changing MyClass.getA() method in this way you should do the trick.

  public A getA() {
    if (a.getS() == null)
      return null;
    return a;
  }

edited Mar 06 '17 at 10:42

answered Mar 06 '17 at 10:32

freedev

25,946
8
108
125

Younes Ouchala · Answer 2 · 2020-10-23T08:49:24.657

0

You need just to add @JsonInclude(JsonInclude.Include.NON_NULL)

@JsonInclude(JsonInclude.Include.NON_NULL)
public class MyClass   implements Serializable {
    private A a;
    private int i;
    //getters and setters
}

public class A  implements Serializable{
    private String s;
    //getters and setters
}

edited Oct 23 '20 at 08:49

answered Mar 06 '17 at 16:57

Younes Ouchala

300
1
4
15

extends an `interface`? – logbasex Oct 21 '20 at 10:45

score 0 · Answer 3 · answered Apr 10 '19 at 08:14

Generate hashCode() and equals() in the desired class.

public class A  extends Serializable{
    private String s;
    // getters and setters
    // hashCode() and equals()
}

Set an Include.CUSTOM in your parent class.

@JsonInclude(value = Include.CUSTOM, valueFilter = A.class)
public class MyClass extends Serializable {
    private A a;
    private int i;
    //getters and setters
}

All empty objects will be excluded and the output will be: {"myClass":{"i":10}}

Jackson ignore serialization of top-level field if all its nested fields are null

3 Answers3