Jackson Error: Java 8 date/time type not supported by default

Learn to fix the error ‘Java 8 date/time type not supported by default‘ while serializing and deserializing Java 8 Date time classes using Jackson.

1. Problem

The error occurs when we serialize a Java object or deserialize JSON to POJO, and the POJO contains new Java 8 date time classes such as LocalDate, LocalTime, LocalDateTime etc.

For example, the following Employee class has LocalDate type field.

public class Employee {

  private Long id;
  private String name;
  private LocalDate dateOfBirth;
}

When we serialize an instance of this class, we get the following exception:

Exception in thread "main" java.lang.IllegalArgumentException: Java 8 date/time type `java.time.LocalDate` not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jsr310" to enable handling (through reference chain: com.howtodoinjava.core.objectToMap.Employee["dateOfBirth"])
	at com.fasterxml.jackson.databind.ObjectMapper ._convert(ObjectMapper.java:4393)
	at com.fasterxml.jackson.databind.ObjectMapper .convertValue(ObjectMapper.java:4324)
	at com.howtodoinjava.core.objectToMap .ObjectToMapUsingJackson.main(ObjectToMapUsingJackson.java:25)

2. Solution

We must add support to new Java 8 classes in two steps to fix this error.

First, add the latest version of com.fasterxml.jackson.datatype:jackson-datatype-jsr310 Maven dependency.

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-jsr310</artifactId>
  <version>2.13.4</version>
</dependency>

Second, register the module JavaTimeModule either with ObjectMapper or JsonMapper based on what you are using.

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new JavaTimeModule());

//or 

JsonMapper jsonMapper = new JsonMapper();
jsonMapper.registerModule(new JavaTimeModule());

After registering the JavaTimeModule, the above error will go away.

3. With Hibernate 6

The above solution may not work if you are facing this issue due to Hibernate 6 that serializes the objects using FormatMapper instances, and the default is JacksonJsonFormatMapper. The JacksonJsonFormatMapper basically uses a Jackson ObjectMapper instance constructed without any additional options.

To fix the issue, we need to create a custom instance of FormatMapper and assign it through a new property hibernate.type.json_format_mapper.

 spring.jpa.properties.hibernate.type.json_format_mapper=com.howtodoinjava.CustomJacksonJsonFormatMapper

And then create the mapper implementation as follows:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.hibernate.type.FormatMapper;
import org.hibernate.type.descriptor.WrapperOptions;
import org.hibernate.type.descriptor.java.JavaType;
import org.hibernate.type.jackson.JacksonJsonFormatMapper;

public class JacksonJsonFormatMapperCustom implements FormatMapper {

    private final FormatMapper delegate;

    public JacksonJsonFormatMapperCustom() {
        ObjectMapper objectMapper = createObjectMapper();
        delegate = new JacksonJsonFormatMapper(objectMapper);
    }

    private static ObjectMapper createObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper()
            .registerModule(new JavaTimeModule())
            .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        return objectMapper;
    }

    @Override
    public <T> T fromString(CharSequence charSequence, JavaType<T> javaType, WrapperOptions wrapperOptions) {
        return delegate.fromString(charSequence, javaType, wrapperOptions);
    }

    @Override
    public <T> String toString(T t, JavaType<T> javaType, WrapperOptions wrapperOptions) {
        return delegate.toString(t, javaType, wrapperOptions);
    }
}

Happy Learning !!