Inject Spring-mananged bean into Hibernate's entity

Question

This won't work (aspect weaving) - SlugGenerator.slugger remains null. Please can someone have a look a this and give me a helping hand?

1. My idea is to weave spring's service into the entity's value generator. I'm aware I can use entity's load event to inject that dependency.
2. I have double checked whether Slugify component is instantiated properly by Spring (I can successfully inject it into controller).

Category.java (entity - domain object):

@Entity(name = "Category")
@Table(name = "category")
@Data
public class Category
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @GeneratorType(type = SlugGenerator.class, when = GenerationTime.ALWAYS)
    private String slug;

    // ...
}

SlugGenerator.java (value generator - instantiated by Hibernate):

@NoArgsConstructor
@Configurable(autowire = Autowire.BY_TYPE)
public class SlugGenerator implements ValueGenerator<String>
{
    @Autowired
    private Slugify slugger;

    @Override
    public String generateValue(Session session, Object owner) {
        Category category = (Category) owner;

        return slugger.slugify(category.getTitle());
    }
}

Slugify.java (Spring-managed service):

@Component
public class SlugifyImpl implements Slugify {
    @Override
    public String slugify(String input)
    {
        // ...
    }
}

DispatcherConf.java (Spring conf.):

public class DispatcherConf extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] {ApplicationConf.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[] {WebConf.class};
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] {"/*"};
    }
}

ApplicationConf.java (Spring conf.):

@Configuration
@EnableSpringConfigured
@Import({DataConf.class})
@ComponentScan(basePackages = {
        "pl.xxx.api.utils",
})
public class ApplicationConf
{
    @Bean
    public RepositoryRestConfigurer repositoryRestConfigurer() {
        return new RepositoryRestConfigurerAdapter() {
            @Override
            public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
                config.setBasePath("/api");
            }
        };
    }
}

WebConf.java (Spring conf.):

@Import(RepositoryRestMvcConfiguration.class)
public class WebConf {
}

build.gradle:

// ...
compile "org.springframework:spring-aspects:$springAspects"
// ...

jvm classpath (among others):

aspectjrt-1.8.13.jar

IntelliJ:

Build,Execution,Deployment > Compiler > Annotation Processors > Enable Annotation Processing set to TRUE

Answer 1

Thanks to the comment of @NándorElődFekete I understood how to achieve my goal - injecting a Spring-managed bean into a by-new-operator-created instance.

It is how I've made it:

Please consider these notes:

• It was not possible to inject the bean into the ValueGenerator implementation (SlugGenerator.java ) - why I don't know. It's an open question :)

• I have successfully injected the Slugify bean into the entity (Category.java) though.

In Spring's configuration I only used @EnableSpringConfigured.

I have chosen to use load-time wevaing (LTW) and consequently I added to my Glassfish domain's config file the following line:

<jvm-options>-javaagent:/usr/local/lib/java/aspectjweaver-1.8.13.jar</jvm-options>

Category.java:

@Entity(name = "Category")
@Table(name = "category")
@Data
@Configurable(autowire = Autowire.BY_TYPE)
public class Category
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @GeneratorType(type = SlugGenerator.class, when = GenerationTime.ALWAYS)
    private String slug;

    @Autowired
    @Transient
    private Slugify slugGenerator;
    // ...
}

class SlugGenerator implements ValueGenerator<String>
{
    @Override
    public String generateValue(Session session, Object owner) {
        Category category = (Category) owner;
        Slugify slugGenerator = category.getSlugGenerator();

        return slugGenerator.slugify(category.getName());
    }
}

Voila, private attribute slugGenerator is populated with the bean of Slugify interface :)

Answer 2

Maybe this approach will be helpful:

@Component
public final class MyBeanUtils {

    @Autowired private ApplicationContext ctx;

    private static MyBeanUtils instance;

    @PostConstruct
    private void registerInstance() {
        instance = this;
    }

    public static <T> T getBean(Class<T> clazz) {
        return instance.ctx.getBean(clazz);
    }

    public static ApplicationContext appCtx() {
        return instance.ctx;
    }
}

Then use Spring beans in unmanaged classes, for example:

public class SlugGenerator implements ValueGenerator<String> {

    private Slugify slugger;

    public SlugGenerator() {
        slugger = MyBeansUtils.getBean(SlugifyImpl.class);
    }

    //...
}