How to erase a type of instance when serializing/deserializing JSON?

Question

I use fasterxml to serialize/deserialize JSON

public class A {
    String field;
    B b;
}

public class B {
    int n;
}

I want to get a JSON in format like this

{
  "field": "abc",
  "n": 123
}

Is it possible?

Answer 1

You can simply use @JsonUnwrapped. No custom serializers are needed:

public class A {
    public String field;
    @JsonUnwrapped
    public B b;
}

public class B {
    public int n;
}

Pay attention to the fields accessibility or it will not work.