JPA Eclipselink JOIN FETCH LAZY relation returning null - jpa

Question

I am always getting NULL from a JOIN FETCH clause in my JPA Query, even though I have everything configured as expected:
#XmlRootElement
#XmlAccessorType(XmlAccessType.PROPERTY)
#Entity
#Table(name = "TB_BANNER_IMAGE")
public class BannerImage extends BaseEntity<Integer> {
protected FileReference fileReference;
private String type;
private String labelTitle;
protected BannerImage() {}
#Id
#TableGenerator(name="genBannerImage", table="TB_ID_GENERATOR",
pkColumnName="ID_NAME", valueColumnName="ID_VAL",
pkColumnValue="TB_BANNER_IMAGE", allocationSize=1)
#GeneratedValue(strategy=GenerationType.TABLE, generator="genBannerImage")
#Column(name = "ID_BANNER_IMAGE", unique = true, nullable = false)
public Integer getId() {
return super.getId();
}
#Override
public void setId(Integer id) {
super.setId(id);
}
#Column(name="TYPE")
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
#OneToOne(fetch=FetchType.LAZY, cascade=CascadeType.ALL)
#JoinColumn(name="ID_FILE_REFERENCE", nullable=false)
public FileReference getFileReference() {
return fileReference;
}
public void setFileReference(FileReference fileReference) {
this.fileReference = fileReference;
}
#Column(name="LABEL_TITLE")
public String getLabelTitle() {
return labelTitle;
}
public void setLabelTitle(String labelTitle) {
this.labelTitle = labelTitle;
}
}
for File Reference Class:
#Entity
#Table(name = "TB_FILE_REFERENCE")
public class FileReference extends BaseNamedEntity<String> {
private String type;
public FileReference() {}
#Id
#TableGenerator(name="genFileReference", table="TB_ID_GENERATOR",
pkColumnName="ID_NAME", valueColumnName="ID_VAL",
pkColumnValue="TB_FILE_REFERENCE", allocationSize=1)
#GeneratedValue(strategy=GenerationType.TABLE, generator="genFileReference")
#Column(name = "ID_FILE_REFERENCE", unique = true, nullable = false)
public String getId() {
return super.getId();
}
#Override
public void setId(String id) {
super.setId(id);
}
#Column(name = "TYPE")
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
}
Service class:
#Path("/banner")
public class BannerImageService extends BaseServiceFacade<BannerImage, Integer> {
#SuppressWarnings("unchecked")
#Override
public Crud<BannerImage, Integer> lookupService() throws ServiceLocatorException {
return ServiceLocator.getInstance()
.getLocalHome(ServicesConstants.BANNER_IMAGE_SERVICE);
}
#Override
protected String getDefaultGetQuery() {
return BannerImageDAO.GET_BY_ID_FETCH_FILE_REF;
}
#Override
protected String getDefaultQuery() {
return BannerImageDAO.GET_ALL_FETCH_FILE_REF;
}
}
get REST method of BaseServiceFacade:
#Override
#GET
#Consumes(MediaType.APPLICATION_JSON)
#Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
#Path("/{id}")
public T get(#PathParam("id") ID id) {
try {
if (!validateID(id)) {
logMessage("Invalid Entity ID: " + id);
return null;
}
String defaultGetQuery = getDefaultGetQuery();
if (defaultGetQuery != null) {
Map<String, Object> mapParams = new HashMap<String, Object>();
mapParams.put("id", id);
List<T> entityList = getService().search(defaultGetQuery, mapParams);
if (entityList != null && entityList.size() == 1) {
T ent = entityList.get(0);
return ent;
} else {
logMessage("Invalid search by Entity ID: " + id);
}
} else {
return getService().findById(clazz, id);
}
} catch (ServiceException e) {
serviceException(e);
} catch (Exception ex) {
logException(ex);
}
return null;
}
And finally the Service Bean EJB which reads from entityManager:
public class BaseServiceBean<T extends IEntity<ID>, ID extends Serializable> implements Crud<T,ID> {
// ... generic methods to be reused by subclasses
#Override
public List<T> search(String queryOrNamedQuery) throws ServiceException {
return search(queryOrNamedQuery, null, 0, 0);
}
#SuppressWarnings("unchecked")
public List<T> search(String namedQueryOrHql, Map<String, Object> parameters, int start, int chunkSize) {
try {
Query query = createQuery(namedQueryOrHql, getQueryType(namedQueryOrHql));
if (start > 0) {
query.setFirstResult(start);
}
if (chunkSize > 0) {
query.setMaxResults(chunkSize);
}
addParameters(query, parameters);
List<T> result = query.getResultList();
afterSearch(result);
return result;
} catch (NoResultException nre) {
nre.printStackTrace();
} catch (ClassCastException cce) {
cce.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void afterSearch(List<T> result) {
}
// etc...
implementation specific class for BannerImageService:
#Stateless(mappedName="ejb/BannerImageService")
public class BannerImageServiceBean extends BaseServiceBean<BannerImage, Integer> implements BannerImageServiceBeanRemote, BannerImageServiceBeanLocal {
#Override
protected void afterSearch(List<BannerImage> result) {
if (result != null && result.size() == 1) {
BannerImage bannerImage = result.get(0);
bannerImage.getFileReference();
}
super.afterSearch(result);
}
// additional code ...
When I try to fetch my BannerImage class together with it's corresponding FileReference member I always get NULL even though in my DB there is an existing foreign key present:
JPQL:
"SELECT a FROM BannerImage a join fetch a.fileReference WHERE a.id = :id";
Generated SQL:
SELECT t1.ID_BANNER_IMAGE, t1.LABEL_TEXT, t1.LABEL_TITLE, t1.TYPE,
t1.ID_FILE_REFERENCE, t0.ID_FILE_REFERENCE, t0.NAME,
t0.TYPE FROM TB_FILE_REFERENCE t0, TB_BANNER_IMAGE
t1 WHERE (t0.ID_FILE_REFERENCE = t1.ID_FILE_REFERENCE) AND t1.ID_BANNER_IMAGE = 1
in my DB the record shows a correct reference:
BANNER_IMAGE:
1;"";"main";"2bdbb063d0d0ee2939c89763945d9d9e";"banner1.png";"image/png"
If I execute :
select * from TB_FILE_REFERENCE where ID_FILE_REFERENCE = '2bdbb063d0d0ee2939c89763945d9d9e'
I can find the record in the DB, although my EclipseLink JPA Implementation always returns null:
EclipseLink Version 2.5.2-M1
This is how the Entity gets passed from Service Layer to the
Can someone help pointing why the JOIN FETCH is not properly working?

Answer 1

I faced a similar issue and looking closely I see that this issue was happening only to entities recently created/saved. Then I figured that it has something to do with eclipselink cache. I solved this problem by adding this line before making a join fetch JPQL query,
em.getEntityManagerFactory().getCache().evictAll();
em.createQuery("SELECT a FROM BannerImage a join fetch a.fileReference WHERE a.id = :id").getResultList();
HTH!