Jackson ignore customized ObjectMapper in API response of Quarkus app

Question

I have the Qurakus app with REST API

@Path("/hello")
public class ExampleResource {

    @GET
    @Consumes(MediaType.APPLICATION_JSON)
    public ObjectNode hello() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        String str = "{\"var\": 0.000000009}";
        ObjectNode object = (ObjectNode) objectMapper.readTree(str);
        return object;
    }
}

With customized Jackson ObjectMapper as follow:

@Singleton
public class RegisterCustomModuleCustomizer implements ObjectMapperCustomizer {
    public void customize(ObjectMapper mapper) {
        mapper.enable(JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN);
    }
}

During response Jackson not invoke customized ObjectMapper, as a result the value returned in scientific notation.

If I use bellow POJO for response, Jackson invoke customized ObjectMapper as needed.

public class Entity {

    public Entity() {
    }

    public Entity(BigDecimal value) {
        this.value = value;
    }

    public BigDecimal value;

    public BigDecimal getValue() {
        return value;
    }

    public void setValue(BigDecimal value) {
        this.value = value;
    }
}

Why Jackson ignore customized ObjectMapper?

Jackson need to invoke customized ObjectMapper.

Answer 1

Implementations of ObjectMapperCustomizer are only applied to ObjectMapper classes that are managed by CDI (meaning they don't work on instances created with new at random parts of the code)

Answer 2

You need to inject the objectMapper managed by Quarkus, and not use your own one:

@Inject ObjectMapper objectMapper;