How use jackson ObjectMapper inside custom deserializer?

Question

I try to write custom jackson deserializer. I want \"look\" at one field and perform auto deserialization to class, see example below:

import com.fasterxml.j         


        

Answer 1

In order to use your own ObjectMapper inside a custom deserializer, you can use Jackson Mix-in Annotations (the DefaultJsonDeserializer interface) to dynamically remove the custom deserializer from the POJO classes, avoiding the StackOverflowError that would otherwise be thrown as a result of objectMapper.readValue(JsonParser, Class).

public class MyDeserializer extends JsonDeserializer {

    private static final ObjectMapper objectMapper = new ObjectMapper();

    static {
        objectMapper.addMixIn(MySuccess.class, DefaultJsonDeserializer.class);
        objectMapper.addMixIn(MyFailure.class, DefaultJsonDeserializer.class);
    }

    @Override
    public MyInterface deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        if (jp.getCodec().readTree(jp).has("custom_field")) {
            return objectMapper.readValue(jp, MyFailure.class);
        } else {
            return objectMapper.readValue(jp, MySuccess.class);
        }           
    }

    @JsonDeserialize
    private interface DefaultJsonDeserializer {
        // Reset default json deserializer
    }

}