Jackson2ObjectMapperBuilder's modulesToInstall function does not eventually override the default configuration

[elue]

Spring Boot version: 2.1.2.RELEASE

The Jackson2ObjectMapperBuilder's modulesToInstall documentation says

 *Specify one or more modules to be registered with the {@link ObjectMapper}.
 * <p>Modules specified here will be registered after
 * Spring's autodetection of JSR-310 and Joda-Time, or Jackson's
 * finding of modules (see {@link #findModulesViaServiceLoader}),
 * allowing to eventually override their configuration.

But when we have this config:

    @Bean
    public ObjectMapper restApiObjectMapper(final Jackson2ObjectMapperBuilder builder,
                                            final LenientOffsetDateTimeDeserializer offsetDateTimeDeserializer) {
        final JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addDeserializer(OffsetDateTime.class, offsetDateTimeDeserializer);

        builder.modulesToInstall(javaTimeModule);
        builder.failOnUnknownProperties(false);
        builder.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        return builder.build();
    }

It is expect that the custom DateTimeDeserializer will get picked up. But still the default one's are used and leading to json parse errors.

[wilkinsona]

Jackson2ObjectMapperBuilder is part of Spring Framework and just auto-configured by Spring Boot. From what you've described thus far, it's not clear if the problem is caused by how Spring Boot is configuring Jackson2ObjectMapperBuilder, a bug in Spring Framework, or a problem in your own code. To help us to home in on the problem, can you please provide a complete and minimal sample that reproduces it as a zip attached to this issue or in a separate repository that we can clone.

[elue]

@wilkinsona , thanks for the response. I will put it as a separate repository as soon as possible.

[elue]

I have created a demo app with 2 object mapper configs. https://github.com/elue/object-mapper-demo.git

[wilkinsona]

Thanks for the sample. It can be made quite a bit more minimal, removing Spring Boot's involvement entirely:

package com.github.example;

import static junit.framework.TestCase.assertNotNull;

import java.io.IOException;
import java.time.OffsetDateTime;
import java.time.format.DateTimeParseException;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.util.StringUtils;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

public class Jackson2ObjectMapperBuilderModuleOverrideTests {

    private static final String DATA = "{\"offsetDateTime\": \"2020-01-01T00:00:00\"}";

    @Test
    public void testObjectMapperForZoneOffset() throws IOException {
    	Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addDeserializer(OffsetDateTime.class, new OffsetDateTimeDeserializer());
        builder.modules(javaTimeModule);
        builder.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        ObjectMapper objectMapper =  builder.build();
        DemoPojo demoPojo = objectMapper.readValue(DATA, DemoPojo.class);
        assertNotNull(demoPojo.getOffsetDateTime());
    }

    @Test
    public void testFailingObjectMapperForZoneOffset() throws IOException {
    	Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addDeserializer(OffsetDateTime.class, new OffsetDateTimeDeserializer());
        builder.modulesToInstall(javaTimeModule);
        builder.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        ObjectMapper objectMapper =  builder.build();
        DemoPojo demoPojo = objectMapper.readValue(DATA, DemoPojo.class);
        assertNotNull(demoPojo.getOffsetDateTime());
    }

}

class OffsetDateTimeDeserializer extends JsonDeserializer<OffsetDateTime> {

    private static final String CURRENT_ZONE_OFFSET = OffsetDateTime.now().getOffset().toString();

    @Override
    public OffsetDateTime deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
        final String value = jsonParser.getValueAsString();
        if (StringUtils.isEmpty(value)) {
            return null;
        }
        try {
            return OffsetDateTime.parse(value);

        } catch (DateTimeParseException exception) {
            return OffsetDateTime.parse(value + CURRENT_ZONE_OFFSET);
        }
    }
}

@JsonDeserialize
class DemoPojo {

    private OffsetDateTime offsetDateTime;

	public OffsetDateTime getOffsetDateTime() {
		return offsetDateTime;
	}

	public void setOffsetDateTime(OffsetDateTime offsetDateTime) {
		this.offsetDateTime = offsetDateTime;
	}

}

testFailingObjectMapperForZoneOffset will fail because the registration of the default JavaTimeModule prevents the custom module with the same typeId from being registered. This looks like a bug in Jackson2ObjectMapperBuilder to me. Well-known modules are registered first which, in Jackson 2.9 at least, prevents the custom module from being registered.

[elue]

Thanks for the feedback. Would you raise an issue for the spring framework then?

[wilkinsona]

I've asked @philwebb to move this issue over to spring-projects/spring-framework.

[jhoeller]

This sounds worth backporting to 5.0.13 and 4.3.23 as well.