greengold greengold - 4 days ago 4
Java Question

Serializing (lazy loaded) entities with Jersey and Jackson

I am using Jersey-Spring4 for my REST API.
This is the relevant pom.xml section I have:

<properties>
<jersey.version>2.25.1</jersey.version>
<guava.version>19.0</guava.version>
<jackson.version>2.25.1</jackson.version>
<slf4j.version>1.7.12</slf4j.version>
<logback.version>1.1.3</logback.version>
<antisamy.version>1.5.3</antisamy.version>
<spring.version>4.3.7.RELEASE</spring.version>
<junit.version>4.12</junit.version>
</properties>

<dependencies>
<dependency>
<groupId>com.openkm</groupId>
<artifactId>sdk4j</artifactId>
<version>2.3</version>
</dependency>

<!-- Servlet -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>

<!-- JAX-RS -->
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.0.1</version>
<scope>compile</scope>
</dependency>

<!-- Jersey -->
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-server</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-json-jackson</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-multipart</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.ext</groupId>
<artifactId>jersey-bean-validation</artifactId>
<version>${jersey.version}</version>
</dependency>

<!--
Note: There is a bug of jersey-spring3 -> https://java.net/jira/browse/JERSEY-2038
-->
<dependency>
<groupId>org.glassfish.jersey.ext</groupId>
<artifactId>jersey-spring3</artifactId>
<version>${jersey.version}</version>
<exclusions>
<exclusion>
<artifactId>spring-context</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
<exclusion>
<artifactId>spring-beans</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
<exclusion>
<artifactId>spring-core</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
<exclusion>
<artifactId>spring-web</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
<exclusion>
<artifactId>jersey-server</artifactId>
<groupId>org.glassfish.jersey.core</groupId>
</exclusion>
<exclusion>
<artifactId>
jersey-container-servlet-core
</artifactId>
<groupId>org.glassfish.jersey.containers</groupId>
</exclusion>
<exclusion>
<artifactId>hk2</artifactId>
<groupId>org.glassfish.hk2</groupId>
</exclusion>
</exclusions>
</dependency>

<!-- Spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.11.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>4.3.5.RELEASE</version>
</dependency>

<!-- Google Guava -->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>${guava.version}</version>
</dependency>
<!-- logging -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>${logback.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback.version}</version>
</dependency>
<dependency>
<groupId>org.owasp.antisamy</groupId>
<artifactId>antisamy</artifactId>
<version>${antisamy.version}</version>
</dependency>

<!-- Apache HTTP Client -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.1</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>fluent-hc</artifactId>
<version>4.5.1</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5.2</version>
</dependency>

<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.2.9.Final</version>
</dependency>

<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.1-api</artifactId>
<version>1.0.0.Final</version>
</dependency>

<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-envers</artifactId>
<version>5.2.9.Final</version>
</dependency>

<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-hibernate5</artifactId>
<version>2.8.4</version>
</dependency>

<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.0.0</version>
</dependency>

<dependency>
<groupId>javax.inject</groupId>
<artifactId>javax.inject</artifactId>
<version>1</version>
</dependency>

<!-- Test -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.hamcrest</groupId>
<artifactId>hamcrest-library</artifactId>
<version>1.3</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.6</version>
</dependency>

<!-- Swagger dependencies -->
<dependency>
<groupId>io.swagger</groupId>
<artifactId>swagger-jersey2-jaxrs</artifactId>
<scope>compile</scope>
<version>1.5.13</version>
</dependency>

<dependency>
<groupId>com.nimbusds</groupId>
<artifactId>nimbus-jose-jwt</artifactId>
<version>4.0</version>
</dependency>

<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.9.9</version>
</dependency>

</dependencies>


now, this how I configure project:

@Configuration("appConfig")
@ComponentScan(value = "com.nws.vedica", lazyInit = true)
@PropertySource({"classpath:swagger.properties", "classpath:vedica.properties"})
@ApplicationPath("/api")
@EnableJpaAuditing(auditorAwareRef="auditorProvider")
public class VedicaConfig extends ResourceConfig {

public VedicaConfig() {
packages("com.nws.vedica");
property(ServletProperties.FILTER_FORWARD_ON_404, true);
register(MultiPartFeature.class);
register(JacksonFeature.class);
// register(MOXyJsonProvider.class);
register(ValidationFeature.class);
register(ValidationConfigurationContextResolver.class);
register(PropertySourcesPlaceholderConfigurer.class);

register(ApiListingResource.class);
register(SwaggerSerializers.class);
}

@Bean
AuditorAware<String> auditorProvider() {
return new AuditorAware<String>() {
@Override
public String getCurrentAuditor() {
return "qwer";
}
};
}

@Bean
public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
return new PersistenceExceptionTranslationPostProcessor();
}
}


Now, my big, annoying, problem is that when I return an entity that has lazy-fetching entities in it I get
WARNING: com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.nws.vedica.model.entity.PartyKind["doc2"]->com.nws.vedica.model.entity.Document2["docType"]->com.nws.vedica.model.entity.DocType["validityRule"]->com.nws.vedica.model.entity.ValidityRule["validFrom"])
Exception.

Okey, I went through many articles and threads that told me I have to use

<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-hibernate5</artifactId>
<version>2.8.4</version>
</dependency>


package to make jackson initialize my entities (which are all FetchType.EAGER, so I don't really know why is this happening).

So when I add
jackson-datatype-hibernate5
dependency and register it in config as follows:

@Bean
public Module datatypeHibernateModule() {
return new Hibernate5Module();
}


But I am still getting the same exception. My opinion is that I need different
datatype-hibernate5
hibernate package for jersey but cannot find which. or register it differently.

Can you advice how to make this work?
Thanks

Answer

It doesn't look like you're using Spring Boot. The Module as a Spring bean is something that will only work with Spring Boot. If you want to configure Jackson with Jersey you should use a ContextResolver where you can configure the ObjectMapper.

@Provider
public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper;

    public ObjectMapperContextResolver() {
        mapper = new ObjectMapper();
        mapper.registerModule(new Hibernate5Module());
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return mapper;
    }
}

Then register it with Jersey

register(ObjectMapperContextResolver.class);