CODEWITHSUNDEEP
ajaxjsonspring
Andna
Andna

Reputation: 6689

Spring MVC + JSON in @ResponseBody + inheritance

I have a class hierarchy. On the top of it there is a an abstract AnswerUnit class. There are two inheriting classes: OpenQuestionAnswer and MultipleChoiceQuestionAnswer.

I have a .jsp form that sends data (object serialized to JSON) to server with AJAX request and a method in controller to handle it. 

@RequestMapping(value = "/test", method = RequestMethod.POST)
    public @ResponseBody
    String testPostMethod(@RequestBody
    OpenQuestionAnswer answer) {
        return "home";
    }

I would like to be able to take "AnswerUnit answer" as the argument (abstract type instead of concrete type, so I could handle request from different views with one method). When I try to do it there is a problem - server respose is

400 BAD REQUEST he request sent by the client was syntactically incorrect.

I think that the reason is that Spring (Jackson?) isn't able to find out which concrete class he should create and use. On the client side I know what type of class I send to server. What is the proper way to tell server which concrete class should be created and filled with my request?

Upvotes: 0

Views: 2474

Answers (1)

mavarazy
mavarazy

Reputation: 7735

I guess I'm late with response, but anyway:)

http://wiki.fasterxml.com/JacksonAnnotations

You can have this using Jackson Polymorphic type handling 

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
@JsonSubTypes(value = {
    @JsonSubTypes.Type(name = "answer", value = OpenQuestionAnswer.class),
    @JsonSubTypes.Type(name = "multiple", value = MultipleChoiceQuestionAnswer.class)
})
public class AnswerUnit
...

But you would need to add "type" field to your client JSON.

Upvotes: 3

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