Question

I need to wrap my json objects to look like this:

{
    "user" : { "id":1 }
}

instead of

{
    "id":1
}

So I set:

mapper.configure(SerializationConfig.Feature.WRAP_ROOT_VALUE, true);

The serialization part is working fine:

mapper.writeValue(writer, user);

But if I do:

User u = mapper.readValue(writer.toString(), User.class);

The returned object contains only null fields. Do I need to configure something else for reading wrapped elements?

Regards

Answer 1

I think you’re looking for the deserialization configuration counterpart to SerializationConfig.Feature.WRAP_ROOT_VALUE. It’s DeserializationConfig.Feature.UNWRAP_ROOT_VALUE. (With Jackson 2+, it’s DeserializationFeature.UNWRAP_ROOT_VALUE.)