Jackson json only convert selected fields and methods

Question

With jackson there is a way to ignore some fields using @JsonIgnore. Is there a way to do the opposite, and only show fields with are annotated? I'm working with an external class with a lot of fields and I only want to select a small subset of them. I'm getting tons of recursion problems (using some type of ORM) where object A -> B -> A -> B -> A .... which are not even necessary to export.

Answer 1

You can configure the object mapper to ignore absolutely everything unless specified by JsonProperty,

public class JacksonConfig {
    
    public static ObjectMapper getObjectMapper(){
    //The marshaller
    ObjectMapper marshaller = new ObjectMapper();

    //Make it ignore all fields unless we specify them
    marshaller.setVisibility(
        new VisibilityChecker.Std(
            JsonAutoDetect.Visibility.NONE,
            JsonAutoDetect.Visibility.NONE,
            JsonAutoDetect.Visibility.NONE,
            JsonAutoDetect.Visibility.NONE,
            JsonAutoDetect.Visibility.NONE
        )
    );

    //Allow empty objects
    marshaller.configure( SerializationFeature.FAIL_ON_EMPTY_BEANS, false );

    return marshaller;
    
    }
}

public class MyObject {

    private int id;
    @JsonProperty
    private String name;
    private Date date;

//Getters Setters omitted

in this case only name would be serialized.

Sample repo, https://github.com/DarrenForsythe/jackson-ignore-everything