On Mon, Oct 15, 2018 at 12:53 AM Jan-Olav Eide <janolave...@gmail.com> wrote:
>
> I was not aware that adding @JsonTypeInfo at the top level was enough, so in
> my case, if I add the D class to that annotation, things work as expected.
> But I guess it still is a bug if one wants to override typeinfo somewhere in
> subclasses. For example, specifying in B that D should instead use
> MINIMAL_CLASS, this also affects B, which will also use MINIMAL_CLASS
Such usage is explicitly not supported, and this is by design.
Contract is that the rules of polymorphic type remain the same through
the hierarchy,
partly since determination of base class does not work well for root
values (since there is no real static type to be found, and runtime
type must be assumed as the base type... at least until Jackson's
annotation flattening system is completely rewritten so it is possible
to know where the "closes" `@JsonTypeInfo` is declared).
> I will file a bug using this more realistic example as a reproducing case.
That would be good, for the original case, where information is
available but not properly used.
Thanks!
-+ Tatu +-
>
> lørdag 13. oktober 2018 23.26.31 UTC+2 skrev Tatu Saloranta følgende:
>>
>> On Fri, Oct 12, 2018 at 7:12 AM Jan-Olav Eide <janol...@gmail.com> wrote:
>> >
>> > Using Jackson 2.9.6, i came across the following, which to me looks like a
>> > bug. Abstract superclass A has two subclasses, B and C, where B again has
>> > a subclass D
>> >
>> > Adding the @JsonTypeInfo and @JsonSubTypes annotations as shown below, I
>> > would expect that B,C and D should all be serialized with a type=name
>> > discriminator field, but it appears that B, which "sits in the middle" of
>> > the object hierarchy is instead serialized using the simple class name as
>> > the type value.
>> >
>> >
>> > JsonTypeInfo(use = NAME, include = PROPERTY, property = "type")
>> > @JsonSubTypes({
>> > @Type(value = B.class, name = "nameB"),
>> > @Type(value = C.class, name = "nameC"),
>> >
>> > })
>> > abstract class A {
>> > private final int i;
>> >
>> > public int getI() {
>> > return i;
>> > }
>> >
>> > public A(int i) {
>> > this.i = i;
>> > }
>> >
>> > }
>> >
>> > @JsonTypeInfo(use = NAME, include = PROPERTY, property = "type")
>> > @JsonSubTypes({
>> > @Type(value = D.class, name = "nameD"),
>> >
>> > })
>> > class B extends A {
>> >
>> > public B(int i) {
>> > super(i);
>> > }
>> >
>> > }
>> >
>> > class C extends A {
>> >
>> > public C(int i) {
>> > super(i);
>> > }
>> >
>> > }
>> >
>> > class D extends B {
>> >
>> > public D(int i) {
>> > super(i);
>> > }
>> >
>> > }
>> >
>> >
>> > Reproduce with the following test:
>> >
>> >
>> > Test
>> > public void testA() throws Exception {
>> > ObjectMapper mapper = new ObjectMapper();
>> >
>> > System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(new
>> > B(42)));
>> >
>> > System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(new
>> > C(42)));
>> >
>> > System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(new
>> > D(42)));
>> >
>> > }
>> >
>> >
>> > which yields :
>> >
>> >
>> > {
>> > "type" : "B",
>> > "i" : 42
>> > }
>> > {
>> > "type" : "nameC",
>> > "i" : 42
>> > }
>> > {
>> > "type" : "nameD",
>> > "i" : 42
>> > }
>>
>> That does look like a bug: `type` for `B` should be `nameB`, and not
>> "default" of class name.
>>
>> As a general rule it is advisable to only add `@JsonTypeInfo` on one
>> supertype (here `A`), but since information
>> here is identical across levels, that is not problematic, just unnecessary.
>> Use of chained @JsonSubTypes is supported and should work.
>>
>> So, could you please file a bug with minimal reproduction (can cut'n
>> paste example)?
>>
>> -+ Tatu +-
>
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