Jackson json only convert selected fields and methods

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.

Yes definitely you can; Create a class with only the feilds you need and add the below property in the object mapper and rest is done.

DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES to false

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

You can use @JsonIgnoreProperties(ignoreUnknown=true) on the pojo class so only the fields which are available in the pojo class will be mapped and resf will be left out.

For example

Json data

{
"name":"Abhishek",
"age":30,
"city":"Banglore",
"state":"Karnatak"
}

pojo class

 @JsonIgnoreProperties(ignoreUnknown=true)
Class Person{
   private int id;
   private String name;
   private String city;
}

Here state in not present in the Person class so that field won't be mapped