JsonTypeInfo not shown in response whit Pageable

Question

I have an abstract class

    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "_type", visible = true, include = As.EXISTING_PROPERTY)
    @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
    @JsonSubTypes({
       @Type(value = B.class, name = "B"),
       ...
    })
    public abstract class A {
      ...
    }

and one of subclasses

@DiscriminatorValue("B")
@JsonTypeName("B")
public class B extends A {
  ...
}

When I want to create one entity I need to specify "_type" property. Which is perfectly good. But when I want a list of A-s, I can't get property "_type" specified in JSON response.

I've tried multiple solutions but cannot find the right way to do it. I've tried to add "_type" property with transactional, tried to add "include = JsonTypeInfo.As.PROPERTY". But still nothing.

Of course for everything I have only one controller for class A.

Can anyone tell me how to get "_type" in get response and other responses?

tnx

I guess your controller method is something like `List loadA(...)` with some `Spring` annotations. Does not it? I noticed type information is skipped for generics when `List` is an root object. Try to create `ListAResponse` class and wrap this `List` using `List aList;` property. After that try to change your controller method to `ListAResponse loadA(...)`. Should work. Which version of `Jackson` and `Spring` do you use? — Michał Ziober, May 24 '19 at 22:13
my return type of method in the controller is Page with Pageable request. Spring version is 2.0.6 and Jackson version is 2.9.9 — Matija Župančić, May 25 '19 at 16:23
I forget to tell you that all work with the list. But when I enter Page and pageable, then I can't get type in the response. — Matija Župančić, May 25 '19 at 16:39
Unfortunately no. There is a possibility to write an aspect that will paste _type on all entities, but this is not the best solution. — Matija Župančić, Nov 20 '19 at 11:29

score 3 · Answer 1 · answered Dec 18 '19 at 15:49

It looks like a bug, not sure where though. Anyway, I have found a workaround for it today.

@GetMapping
public Page<MyObject> findAll(Pageable pageable) {
   Page<MyObject> page = ...;
   return new PageImpl<>(page.getContent(), pageable, page.getTotalElements()) {};
}

Note that the new instance of anonymous class extending PageImpl is being returned here (not a new instance of PageImpl) to prevent type erasure.

JsonTypeInfo not shown in response whit Pageable

1 Answers1