From: Franz Wong <franzwong_at_gmail.com>
Date: Mon, 27 Dec 2010 23:58:55 +0800

I have written a method which returns an array. This array contains
different subclass object instances. However, the json output only contains
the properties of the superclass.

I have created another program, trying to use jackson's ObjectMapper to
generate json. The output contains both properties of superclass and
subclass. And jackson's output does not contain a "person" property name
field.

How can I generate the output as same as the output generated by jackson
library?

Thanks.
Franz

Here is the example.

The model class :

@XmlRootElement
public class Person {
  private String name;
  /* getter and setter */
}

public class Staff {
  private int rank;
  /* getter and setter */
}

The restful service :

@Path("/test")
@POST
@Produces(MediaType.APPLICATION_JSON)
public Person[] test() {
    Staff staff = new Staff();
    staff.setName("Franz Wong");
    staff.setRank(5);

    Staff staff2 = new Staff();
    staff2.setName("Peter Wong");
    staff2.setRank(1);

    Person[] persons = new Person[2];
    persons[0] = staff;
    persons[1] = staff2;

    return persons;
}

Jackson version for testing code :

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.writeValue(System.out, persons); // setup of persons array is
the same

The json output:
{"person":[{"name":"Franz Wong"},{"name":"Peter Wong"}]}

The json output from jackson's ObjectMapper.

[{"rank":5,"name":"Franz Wong"},{"rank":1,"name":"Peter Wong"}]