Handling Null Field Values in Jackson Serialization

Jackson, a popular Java serialization library, provides various configuration options to tailor its serialization behavior. One common scenario is suppressing the serialization of field values that are null. This ensures that only non-null properties are included in the serialized output.

Configuring Jackson for Null Value Suppression

There are two primary approaches to instruct Jackson to ignore null field values during serialization.

1. Using SerializationInclusion:

ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

This global configuration applies to all fields in all classes that are processed by the ObjectMapper. It ensures that any field with a null value will be omitted from the serialized output.

2. Using the @JsonInclude Annotation:

@JsonInclude(Include.NON_NULL)
public class SomeClass {
    private String someValue;
}

Applying the @JsonInclude annotation to a class or getter method allows you to specify the serialization behavior for specific properties or subclasses. By setting Include.NON_NULL, it indicates that only non-null values for that field should be serialized.

Alternative Approaches

Alternatively, you can use the @JsonInclude annotation in the getter method for a particular property to conditionally serialize the property only when its value is not null.

@JsonInclude(value = JsonInclude.Include.NON_NULL, condition = JsonInclude.Include.Condition.NON_NULL)
public String getSomeValue() {
    return someValue;
}

Additional Considerations

Note that these configurations do not affect the deserialization process. If a null value is encountered during deserialization, it will still be set in the corresponding field. To control deserialization behavior, refer to the Jackson documentation for @JsonIgnoreProperties and @JsonIgnore.