Spring @RequestBody containing a list of different types (but same interface)

Question

Let's say that I have a domain class :

    public class Zoo{         private List<Animal> animals;         .... 

where an Animal is an interface with different implementations (Cat,Dog). Let's say that I want to be able to save a Zoo object :

    @RequestMapping(value = "/zoo", method = RequestMethod.POST)     public @ResponseBody void save(@RequestBody Zoo zoo) {     .... 

and I want to send a json - something like :

    {         animals:[             {type:'Cat', whiskers-length:'3'},             {type:'Dog', name:'Fancy'}         ]     } 

How can I tell spring MVC to map animal to Cat type when type=='Cat' and to map it to a Dog class when type=='Dog'?

Answer 1

You should use the Jackson annotations @JsonTypeInfo and @JsonSubTypes to achieve polymorphic json. The annotations go on the Animal base class.

@JsonTypeInfo(use = Id.NAME, include = As.PROPERTY, property = "type") @JsonSubTypes({@JsonSubTypes.Type(value = Dog.class, name = "Dog"),         @JsonSubTypes.Type(value = Cat.class, name = "Cat")}) public abstract class Animal {  } 

Answer 2

There is a simpler annotation out now:

@JsonRootName("dog") public class Dog extends Animal {...} 

The reference to the annotation can be found on fasterxml.github