Deserialization of a polymorphic type based on presence of a property

I’d like a feature on jackson for deserialization of polymorphic type where type selection strategy should be based on presence of a property. I know this was mentioned before but there was no consensus about how it should be solved.

Example: For jsons like: {'foo':''} {'bar':''}

and type definitions like:

@JsonSubTypes({
        @JsonSubTypes.Type(value=Foo.class, name="foo"),
        @JsonSubTypes.Type(value=Bar.class, name="bar"),
})
interface FooBar {
}

@Value
class Foo {
    private final String foo;
}

@Value
class Bar {
    private final String bar;
}

When I deserialise FooBar with {'foo':''} I should get an instance of a Foo and similar for {'bar':''} I should get an instance of a Bar.

I have a working prototype where you have to specify a new custom deserialiser like:

public class FooBarDeserialiser extends PresentPropertyPolymorphicDeserialiser<FooBar> {

    public FooBarDeserialiser() {
        super(FooBar.class);
    }
}

and this is a valid approach, but a better one, in my opinion, would be if this had first class support for example with JsonTypeInfo:

@JsonTypeInfo(use = JsonTypeInfo.Id.PROPERTY_NAME) // or PROPERTY_NAME_PRESENCE
@JsonSubTypes({
        @JsonSubTypes.Type(value=Foo.class, name="foo"),
        @JsonSubTypes.Type(value=Bar.class, name="bar"),
})
interface FooBar {
}

Thoughts?

[RobertDiebels]

Upvoted. This would be extremely useful when you:

1. Don’t want to include type information in your JSON.
2. Don’t want to write a deserializer to handle all this.

[lpandzic]

Yes I agree, but the functionality should be added in some form to the jackson itself, something like @JsonTypeInfo(use=Id.PRESENCE, include=As.PROPERTY) or something like that.