Lazy loading doesn't work in @Service class

Question

i am using hibernate 3.5.1-Final, with spring 3.0.5.RELEASE and i am using the following configuration for OpenSessionInViewFilter:

<filter>
    <filter-name>hibernateFilter</filter-name>
    <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
    <init-param>
      <param-name>sessionFactoryBeanName</param-name>
      <param-value>sessionFactory</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>hibernateFilter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>FORWARD</dispatcher>
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>ERROR</dispatcher>
  </filter-mapping>

suppose that i have the following entity:

@SuppressWarnings("serial")
@Entity
@Table(name = "adpage", catalog = "mydb")
public class Adpage implements java.io.Serializable {

    @Id
    @Column(name = "pkid", nullable = false, length = 50)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(fetch = FetchType.EAGER)
    private long pageId;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "audio_file_id", unique = true, nullable = true)
    private AudioFile audioFile ;

}

and my backing bean is as follows:

@Component("myBean")
@Scope("view")
public class MyBean {

    @Autowired
    private AdPageDao adPageDao;

    @Autowired
    private AdPageService adPageService;

     public void preRender() {
                adPageObj = adPageDao.getAdPageByID(adPageId);
    }

    public void deleteAdPage(Adpage adPage) {
        adPageService.deleteAdPage(adPage);
    }



}

my service is as follows:

@Service
public class AdPageService {

    @Autowired
    private AudioFileDao audioFileDao;

    public void deleteAdPage(Adpage adPage) {


        if (adPage.getAudioFile() != null) {
            log.debug("deleting audio file: "
                    + adPage.getAudioFile().getName() + " for adpage: " // exception here
                    + adPage.getName());
            audioFileDao.deleteAudioFile(adPage.getAudiofileref());
            GeneralUtils.deleteFilePhysically(adPage.getAudioFile()
                    .getName();
        }

    }


}

my xhtml page is as follows:

<f:event type="preRenderView" listener="#{myBean.preRender}" />
<ice:panelGrid columns="2">

                 <ice:outputLabel id="fileName">File Name:</ice:outputLabel>
                 <ice:outputText value="#{myBean.adPageObj.audioFile.originalName}"></ice:outputText>

                 <ice:outputLabel id="fileLength">File Length:</ice:outputLabel>
                 <ice:outputText value="#{myBean.adPageObj.audioFile.length}"></ice:outputText>

                 <ice:outputLabel id="fileDesc">Description:</ice:outputLabel>
                 <ice:outputText value="#{myBean.adPageObj.audioFile.description}"></ice:outputText>

               </ice:panelGrid>

in the xhtml page the lazy loading works with no problems, and the file data is displayed correctly, but when deleting the file, i am getting the following error in the delete service method: AdPageService.deleteAdPage

Could not initialize proxy - no Session

please advise how to fix this error.

Answer 1

If the AdPage object was loaded in your view (a previous Hibernate session due to the OpenSessionInViewFilter), then lazy-loading does not work because the entity is "detached" now.

To solve the lazy-loading problem you could do:

1. reattach the entity to the current Hibernate session
2. do an eager fetch before to ensure all attributes are loaded
3. reload the entity by it's id (pageId here)

I'd go for option 3 (reload by it's id) to get a fresh entity (which could have changed while displaying / submitting the form).