How to use @JsonIdentityInfo with circular references?

Question

I am trying to use the @JsonIdentityInfo from Jackson 2 as described here.

For testing purposes I created the following two classes:

public class A
{         


        

Answer 1

It seems jackson-jr has a subset of Jackson's features. @JsonIdentityInfo must not have made the cut.

If you can use the full Jackson library, just use a standard ObjectMapper with the @JsonIdentityInfo annotation you suggested in your question and serialize your object. For example

@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@id")
public class A {/* all that good stuff */}

@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@id")
public class B {/* all that good stuff */}

and then

A a = new A();
B b = new B(a);
a.setB(b);
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(a));

will generate

{
    "@id": 1,
    "b": {
        "@id": 2,
        "a": 1
    }
}

where the nested a is referring to the root object by its @id.