Enable Jackson Deserialization of Empty Objects to Null

How to tell Jackson to ignore empty object during deserialization?

I would use a JsonDeserializer. Inspect the field in question, determine, if it is emtpy and return null, so your ContainedObject would be null.

Something like this (semi-pseudo):

 public class MyDes extends JsonDeserializer<ContainedObject> {

        @Override
        public String deserialize(JsonParser jsonParser, DeserializationContext context) throws IOException, JsonProcessingException {
            //read the JsonNode and determine if it is empty JSON object
            //and if so return null

            if (node is empty....) {
                return null;
            }
            return node;
        }

    }

then in your model:

 public class Entity {
    private long id;
    private String description;

    @JsonDeserialize(using = MyDes.class)
    private ContainedObject containedObject;

   //Contructor, getters and setters omitted

 }

Hope this helps!

Why Doesn't Setting Jackson to Accept Empty Lists as Null Work?

For this example case, my problem was the @EnableWebMvc annotation within the ExampleApplication class. Removing that annotation allowed me to successfully send an empty array to my endpoint, which then received it as a null object.

Note

My original problem still exists within my company's application, even after removing the annotation. However, it seems like this may be an issue with a different setting that might be clashing with ...accept-empty-arrays-as-null-object.

Do not include empty object to Jackson

Without a custom serializer, jackson will include your object.

Solution 1 : Replace new object with null

person.setDetails(new PersonDetails());

with

person.setDetails(null);

and add

@JsonInclude(Include.NON_NULL)
public class Person {

Solution 2: Custom serializer

public class PersonDetailsSerializer extends StdSerializer<PersonDetails> {

    public PersonDetailsSerializer() {
        this(null);
    }

    public PersonDetailsSerializer(Class<PersonDetails> t) {
        super(t);
    }

    @Override
    public void serialize(
            PersonDetails personDetails, JsonGenerator jgen, SerializerProvider provider)
            throws IOException, JsonProcessingException {
        // custom behavior if you implement equals and hashCode in your code
        if(personDetails.equals(new PersonDetails()){
           return;
        }
        super.serialize(personDetails,jgen,provider);
    }
}

and in your PersonDetails

public class Person {
    private String name;
    @JsonSerialize(using = PersonDetailsSerializer.class)
    private PersonDetails details;
}

Jackson Mapper - how to fail on null or empty values

There is an option called: FAIL_ON_NULL_FOR_CREATOR_PARAMETERS.

So I assume it would be accessible at: DeserializationConfig.Feature.FAIL_ON_NULL_FOR_CREATOR_PARAMETERS;

Or in yml:

jackson:
    serialization:
      indent-output: false
    deserialization:
      fail-on-unknown-properties: true
      fail-on-missing-creator-properties: true
      fail-on-null-creator-properties: true

This works on all types, strings, ints, doubles etc..

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