Jackson-datatype-Hibernate

Project to build Jackson module (jar) to support JSON serialization and deserialization of Hibernate (http://hibernate.org) specific datatypes and properties; especially lazy-loading aspects.

Status

As of version 2.0 module is usable and used by non-trivial number of developers and projects.

Note: Hibernate 3.x, 4.x and 5.x are supported (5.x starting with Jackson 2.6), but they require different jar, and Maven artifact names (and jar names differ). This document refers to "Hibernate 4" version, but changes with 3.x or 5.x should require little more than replacing "4" in names with "3" or "5".

Usage

Maven dependency

To use module on Maven-based projects, use following dependency:

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-hibernate4</artifactId>
  <version>2.9.0</version>
</dependency>    

or whatever version is most up-to-date at the moment; note that you need to use "jackson-datatype-hibernate3" for Hibernate 3.x, or "jackson-datatype-hibernate5" for Hibernate 5.x

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-hibernate5</artifactId>
    <version>2.9.8</version>
</dependency>

Registering module

Like all standard Jackson modules (libraries that implement Module interface), registration is done as follows:

ObjectMapper mapper = new ObjectMapper();
// for Hibernate 4.x:
mapper.registerModule(new Hibernate4Module());
// or, for Hibernate 5.x
mapper.registerModule(new Hibernate5Module());
// or, for Hibernate 3.6
mapper.registerModule(new Hibernate3Module());

after which functionality is available for all normal Jackson operations.

Avoiding infinite loops

• http://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion

Using with Spring MVC

Although more common way would be to register the module explicitly, it is alternatively possible to just sub-class ObjectMapper and register the module in constructor.

public class HibernateAwareObjectMapper extends ObjectMapper {
    public HibernateAwareObjectMapper() {
        // This for Hibernate 5; change 5 to 4 or 3 if you need to support
        // Hibernate 4 or Hibernate 3 instead
        registerModule(new Hibernate5Module());
    }
}

Then add it as the objectmapper to be used

    <mvc:annotation-driven>
        <mvc:message-converters>
            <!-- Use the HibernateAware mapper instead of the default -->
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="path.to.your.HibernateAwareObjectMapper" />
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

If mvc:annotation-driven is not being used, it can be added as a jsonconverter to the messageconverters of RequestMappingHandlerAdapter.

Other

Project Wiki contains links to Javadocs and downloadable jars (from Central Maven repository).