Develop Reference

Hibernate: Getting result using a specific field

I've been following a lot of tutorial on how to get a list of result by referencing a specific column in the table.
I have this table.
I want to get the list of result with a plan_code "TEST123"
This is my code:
PlanRepository.java
public interface PlanCoverageRepository extends CrudRepository<PlanCoverage, Long> {
List<PlanCoverage> findAllByPlan_code(String plan_code);
}
PlanCoverageService.java
public interface PlanCoverageService {
public List<PlanCoverage> getAllPlanCoverageByPlanCode(String plan_code);
}
PlanCoverageServiceImpl.java
#Service
#Transactional
public class PlanCoverageServiceImpl implements PlanCoverageService {
#Override
public List<PlanCoverage> getAllPlanCoverageByPlanCode(String plan_code) {
return (List<PlanCoverage>) planCoverageRepository.findAllByPlan_code(plan_code);
}
}
PlanCoverageController.java
#Controller
#RequestMapping(value="/admin")
public class PlanCoverageController {
#Autowired
PlanCoverageService planCoverageService;
#RequestMapping(value="/Test/{plan_code}", method=RequestMethod.GET)
public ModelAndView test(#PathVariable String plan_code) {
ModelAndView model = new ModelAndView();
PlanCoverage planCoverage = (PlanCoverage) planCoverageService.getAllPlanCoverageByPlanCode(plan_code);
model.addObject("planCoverageForm",planCoverage);
model.setViewName("plan_coverage_form");
return model;
}
}
PlanCoverage.java
#Entity
#Table(name="plan_coverage")
public class PlanCoverage {
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
private long coverage_id;
#Column(name="plan_code")
private String plan_code;
#Column(name="coverage_description")
private String coverage_description;
/..getters and setters
#ManyToOne()
#JoinColumn(name="plan_code", referencedColumnName = "plan_code",insertable=false, updatable=false)
private Plan plan;
public Plan getPlan() {
return plan;
}
public void setPlan(Plan plan) {
this.plan = plan;
}
}
Please help me. I've been stuck with these for a few days and non of the tutorials seems to work on me. Thank you so much!!

You have messed up with the convention that spring boot is using to compose query methods. The case of the fields in the entity should follow the lower camel-case scheme, like so:
#Column(name="plan_code")
private String planCode;
and then the query method in PlanCoverageRepository should be:
List<PlanCoverage> findAllByPlanCode(String planCode);

Java JPA Preventing Proxies from calling db

I have a spring boot (1.5.4.RELEASE) project using Java 8. I have an entity and it's related domain class like this:
#Entity
#Table(name = "Foo", schema = "dbo")
public class FooEntity implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "Id")
private int id;
#Column(name="Name")
private String name;
#Column(name="Type")
private String type;
#Column(name="Color")
private String color;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "Car")
private Car car;
//getter and setter
}
public class Foo {
private int id;
private String name;
private String type;
private String color;
private Car car;
//Constructors and getters
}
I want to create a repository that fetches this Foo object from the DB but only fetching the complex fields if the user asks for them to prevent unnecessary join statements. The repo looks like this:
import static com.test.entities.QFooEntity.fooEntity;
import static com.test.entities.QCarEntity.carEntity;
#Repository
public class FooRepository {
private final JPAQuery<FooEntity> query = createQuery().from(fooEntity);
public FooRepository getFooByName(String name) {
query.where(fooEntity.name.eq(name));
return this;
}
public FooRepository withCar() {
query.leftJoin(fooEntity.car, carEntity).fetchJoin();
return this;
}
public Foo fetch() {
FooEntity entity = query.fetchOne();
return FooMapper.mapEntityToDomain().apply(entity);
}
}
So a barebones call for a Foo object will return the Entity with values for all the fields except for the car field. If the user wants car information then they have to explicitly call withCar.
Here is the mapper:
public class FooMapper {
public static Function<FooEntity, Foo> mapEntityToDomain() {
return entity -> {
return new Foo(e.getId(), e.getName(), e.getType(), e.getColor(), e.getCar());
};
}
}
The problem is when you do e.getCar() if the value is not there (i.e. there's a proxy present) JPA will go out and fetch it for you. I don't want this to be the case. It will just grab the values and map them to the domain equivalent if it's not there then null.
One solution that I've heard (and tried) is calling em.detach(entity); however, this doesn't work as I intended because it throws an exception when you try to access getCar and I've also heard this is not best practice.
So my question is what is the best way to create a repo using a builder pattern on a JPA entity and not have it call the DB when trying to map.

You could create a utility method that will return null if the given object is a proxy and is not initialized:
public static <T> T nullIfNotInitialized(T entity) {
return Hibernate.isInitialized(entity) ? entity : null;
}
Then you can call the method wherever you need it:
return new Foo(e.getId(), e.getName(), e.getType(), e.getColor(), nullIfNotInitialized(e.getCar()));

Just map it to a new object and leave out the Car relation, this is the standard approach. You can use MapStruct and just ignore the car field during mapping: http://mapstruct.org/documentation/stable/reference/html/#inverse-mappings

Just don't map the car... Map a field holding the ID and use another method to get the actual Car. I would use a distinctive method name, to differentiate it from the other getters.
class FooEntity {
#Column
private int carId;
public int getCarId() {
return carId;
}
public void setCarId(int id) {
this.carId = id;
}
public Car fetchCar(CarRepository repo) {
return repo.findById(carId);
}
}

You can write query on top of JPA
#Query("select u from Car c")
import org.springframework.data.repository.CrudRepository;
import com.example.model.FluentEntity;
public interface DatabaseEntityRepository extends CrudRepository<FooEntity , int > {
}

As you said
I don't want this to be the case. It will just grab the values and map them to the domain equivalent, if it's not there then null.
Then you just set it to null, because the field car will always not be there.
Otherwise, if you mean not there is that the car not exists in db, for sure a subquery(call the proxy) should be made.
If you want to grab the car when call Foo.getCar().
class Car {
}
class FooEntity {
private Car car;//when call getCar() it will call the proxy.
public Car getCar() {
return car;
}
}
class Foo {
private java.util.function.Supplier<Car> carSupplier;
public void setCar(java.util.function.Supplier<Car> carSupplier) {
this.carSupplier = carSupplier;
}
public Car getCar() {
return carSupplier.get();
}
}
class FooMapper {
public static Function<FooEntity, Foo> mapEntityToDomain() {
return (FooEntity e) -> {
Foo foo = new Foo();
foo.setCar(e::getCar);
return foo;
};
}
}
Make sure you have the db session ,when you call Foo.getCar()

You could try adding state to your repository and influence the mapper. Something like this:
import static com.test.entities.QFooEntity.fooEntity;
import static com.test.entities.QCarEntity.carEntity;
#Repository
public class FooRepository {
private final JPAQuery<FooEntity> query = createQuery().from(fooEntity);
private boolean withCar = false;
public FooRepository getFooByName(String name) {
query.where(fooEntity.name.eq(name));
return this;
}
public FooRepository withCar() {
query.leftJoin(fooEntity.car, carEntity).fetchJoin();
withCar = true;
return this;
}
public Foo fetch() {
FooEntity entity = query.fetchOne();
return FooMapper.mapEntityToDomain(withCar).apply(entity);
}
}
In your mapper, you then include a switch to enable or disable car lookups:
public class FooMapper {
public static Function<FooEntity, Foo> mapEntityToDomain(boolean withCar) {
return e -> {
return new Foo(e.getId(), e.getName(), e.getType(), e.getColor(), withCar ? e.getCar() : null);
};
}
}
If you then use new FooRepository().getFooByName("example").fetch() without the withCar() call, e.getCar() should not be evaluated inside FooMapper

You may want to use the PersistentUnitUtil class to query if an attribute of entity object is already loaded or not. Based on that you may skip the call to corresponding getter as shown below. JpaContext you need to supply to user entity bean mapper.
public class FooMapper {
public Function<FooEntity, Foo> mapEntityToDomain(JpaContext context) {
PersistenceUnitUtil putil = obtainPersistentUtilFor(context, FooEntity.class);
return e -> {
return new Foo(
e.getId(),
e.getName(),
e.getType(),
e.getColor(),
putil.isLoaded(e, "car") ? e.getCar() : null);
};
}
private PersistenceUnitUtil obtainPersistentUtilFor(JpaContext context, Class<?> entity) {
return context.getEntityManagerByManagedType(entity)
.getEntityManagerFactory()
.getPersistenceUnitUtil();
}
}

Why ResponseEntity calls hibernate while lazy loading active

Below is the DAO. I am getting the first UppeningUsers object. Note that here for this function I do not want to return peopleWhoBlockedMe set which is located inside the UppeningUsers..
But in different functions I would like to return that information. Note that Both of them are LAZY fetching. With evict I tried to detach the object but still it did not work.
First of all RESTcontroller is below. Then the DAO code is below. Then two entity descriptions are below.
Question is: I see that until
return new ResponseEntity(returned, HttpStatus.OK);
There is only one query which is the typical select. I do not want hibernate to go and take also UserBlock information of that specific UppeningUser. Because it is not needed for this service response. However even though it is lazy loading for some reason
return new ResponseEntity(returned, HttpStatus.OK);
calls the hibernate. I dont know why in restcontroller still it is connected to the database. I tried evict but didnt work.
The json response is
{"id":7,"peopleWhoBlockedMe":[{"blockedId":7}]}
But I do not want for this function to return this peopleWhoBlockedMe. It can be empty.
PLEASE NOTE that in other service for example I will explictly request this peopleWhoBlockedMe but just for this business logic I do not need this information. So what I can do to prevent this so whenever I actually want to call peopleWhoBlockedMe I can get it. Not automaticly.
#RestController
public class TempController {
#Autowired
UppeningUsersService uppeningUsersService;
#RequestMapping(value = "/testing", method = RequestMethod.GET)
public ResponseEntity<UppeningUsers> getPhotos() {
try {
UppeningUsers returned = uppeningUsersService.getUsersDetailsPartial();
return new ResponseEntity<UppeningUsers>(returned, HttpStatus.OK);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
This part is the DAO.
#Repository
public class UppeningUsersDAO {
#Autowired
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sf) {
this.sessionFactory = sf;
}
/**
* Get Existing user. Return error if there is not.
* #param incomingUser user who requested access.
* #return returns the guy information. All information.
*/
#Transactional
public UppeningUsers getUserDetails() throws Exception {
Session session = this.sessionFactory.getCurrentSession();
Query query = session.createQuery("from UppeningUsers ");
UppeningUsers returning = (UppeningUsers) query.list().get(0);
session.evict(returning);
return returning;
}
}
The main table is this one..
#Entity
#Table(name = "uppening_users")
#Proxy(lazy = true)
public class UppeningUsers {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private
int id;
#OneToMany(mappedBy = "blockedId",cascade =CascadeType.ALL, fetch = FetchType.LAZY)
private Set<UserBlocks> peopleWhoBlockedMe;
public UppeningUsers() {
super();
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Set<UserBlocks> getPeopleWhoBlockedMe() {
return peopleWhoBlockedMe;
}
public void setPeopleWhoBlockedMe(Set<UserBlocks> peopleWhoBlockedMes) {
this.peopleWhoBlockedMe = peopleWhoBlockedMes;
}
}
Now here is the other table.
#Entity
#Table(name="user_blocks")
#Proxy(lazy = true)
public class UserBlocks {
#Id
#Column(name="id")
#GeneratedValue(strategy= GenerationType.IDENTITY)
int id;
#Column(name = "blocked_id",insertable = false,updatable = false)
private int blockedId;
public int getBlockedId() {
return blockedId;
}
public void setBlockedId(int blockedId) {
this.blockedId = blockedId;
}
}
UPDATE: 2 forgot to add the service
#Service("uppeningUserService")
public class UppeningUsersService {
#Autowired
UppeningUsersDAO uppeningUsersDAO;
public UppeningUsers getUsersDetailsPartial( ) throws Exception {
return uppeningUsersDAO.getUserDetails();
}
}

Jens is right about her sentence. The layer methodology and writing business objects fix the issue. Thank you.

NullPointerException thrown on flush after upgrading to Hibernate 4.1.3 Final

I have just completed an upgrade from Hibernate 3.6 to 4.1.3 Final and at first everything seemed to go fine. However, one of my colleagues recently tested this an in one scenario he gets a NullPointer being thrown from within Hibernate (and this exception was not being thrown before we upgraded for the exact same DB). It is an incredibly strange scenario. We have an entity called BlogPost that looks like the below and it extends some mapped superclasses (that I have also included):
#Entity
#Table(name = "blog_post")
public class BlogPost extends CommunityModelObject implements HasFeedPost {
#Lob
private String title;
#Lob
private String content;
#Enumerated
#Column(nullable = false)
private CBlogPost.Status status = CBlogPost.Status.UNPUBLISHED;
// Reference to the feed post that indicates that this blog post has been published
#OneToOne
#JoinColumn(name = "feed_post_id")
private FeedPost feedPost;
#ManyToOne
#JoinColumn(name = "posted_by_employee_id")
private Employee postedBy;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public CBlogPost.Status getStatus() {
return status;
}
public void setStatus(CBlogPost.Status status) {
this.status = status;
}
#Override
public FeedPost getFeedPost() {
return feedPost;
}
#Override
public void setFeedPost(FeedPost feedPost) {
this.feedPost = feedPost;
}
public Employee getPostedBy() {
return postedBy;
}
public void setPostedBy(Employee postedBy) {
this.postedBy = postedBy;
}
}
#Filter(name = "tenantFilter", condition = "(tenant_id = :tenantId or tenant_id is null)")
#MappedSuperclass
public abstract class CommunityModelObject extends ModelObject {
#IndexedEmbedded(prefix = "tenant", indexNullAs = IndexedEmbedded.DEFAULT_NULL_TOKEN)
#ManyToOne
#JoinColumn(name = "tenant_id")
protected Tenant tenant;
public Tenant getTenant() {
return tenant;
}
public void setTenant(Tenant tenant) {
this.tenant = tenant;
}
/**
* If the Tenant is null then it can be accessed / viewed by the entire "community" / user base
*/
public boolean isCommunityObject() {
return tenant == null;
}
}
#MappedSuperclass
public abstract class ModelObject extends BaseModelObject {
#Id
#GeneratedValue
private Long id;
#Override
public long getId() {
return (id == null ? 0 : id);
}
public void setId(long id) {
this.id = (id == 0 ? null : id);
}
}
#MappedSuperclass
public abstract class BaseModelObject implements java.io.Serializable {
// This annotation ensures that a column is not associated with this member (simply omitting the #Column annotation is not enough since
// that annotation is completely optional)
#Transient
private boolean doNotAutoUpdateDateUpdated = false;
#Version
protected int version;
#Column(name = "date_created")
protected Date dateCreated;
#Column(name = "date_updated")
protected Date dateUpdated;
public abstract long getId();
public int getVersion() {
return version;
}
public void setVersion(int version) {
this.version = version;
}
public Date getDateCreated() {
return dateCreated;
}
public Date getDateUpdated() {
return dateUpdated;
}
/**
* This will set the dateUpdated to whatever is passed through and it will cause the auto update (pre-update) to NOT occur
*
* #param dateUpdated
*/
public void setDateUpdated(Date dateUpdated) {
doNotAutoUpdateDateUpdated = true;
this.dateUpdated = dateUpdated;
}
public void touch() {
// By setting date updated to null this triggers an update which results in onUpdate being called and the nett
// result is dateUpdated = new Date()
dateUpdated = null;
}
#PrePersist
protected void onCreate() {
dateCreated = new Date();
}
#PreUpdate
protected void onUpdate() {
if (!doNotAutoUpdateDateUpdated) {
dateUpdated = new Date();
}
}
#Override
public boolean equals(Object obj) {
long id = getId();
if (id == 0) {
return this == obj;
}
//Use Hibernate.getClass() because objects might be proxies
return obj != null &&
obj instanceof BaseModelObject &&
Hibernate.getClass(this) == Hibernate.getClass(obj) &&
getId() == ((BaseModelObject)obj).getId();
}
#Override
public int hashCode() {
Long id = getId();
return id == 0 ? super.hashCode() : id.intValue();
}
#Override
public String toString() {
return getClass().getSimpleName() + "-" + getId();
}
}
The strangest thing is happening when I query BlogPost in some scenarios. If I run the query below, for example, in isolation then it works fine but if I run it in amongst a bunch of other queries then I get the exception below:
select b from BlogPost b
java.lang.NullPointerException
at org.hibernate.event.internal.DefaultFlushEntityEventListener.isUpdateNecessary(DefaultFlushEntityEventListener.java:240)
at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:163)
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:225)
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:99)
at org.hibernate.event.internal.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:55)
at org.hibernate.internal.SessionImpl.autoFlushIfRequired(SessionImpl.java:1153)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1208)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:256)
Now the kicker is that if I take all of the fields from all of the mapped superclasses that I listed above and put them directly into BlogPost and make BlogPost just extend nothing and implement java.io.Serializable then everything works perfectly. This leads me to believe that the bug is either related to mapped superclasses or the Hibernate filter that I am applying to CommunityModelObject.
Any ideas as to how to solve this? I am assuming that it is a newly introduced bug in Hibernate but I may be wrong. This is causing major issues for us since we need to upgrade asap in order to upgrade Hibernate Search which we need to do for a critical bug fix.
Also note that the DB we are using is MySQL with the following custom dialect that I wrote when doing this upgrade to handle our BIT columns:
public class MySQL5InnoDBDialectExt extends MySQL5InnoDBDialect {
private static final String BIT_STRING = "bit";
public MySQL5InnoDBDialectExt() {
super();
registerColumnType(Types.BOOLEAN, BIT_STRING);
}
}
Thanks,
Brent

I sorted this issue out, found the problem by fluke. Here is the resolution as I posted it on the Hibernate forum:
I found the issue. It does not seem to be related to interceptors,
rather to either caching or instrumentation. Basically our app
automatically includes all entities within a very specific package in
our caching scheme and the same classes in our instrumentation. We
generally have all of our entities in this package, however this one
which was causing the issue was the only one not included in this
package. The previous version of EhCache / Hibernate that we were
using seemed ok with this, but after upgrading it caused issues.
Anyway, the entity was in the incorrect package, when I refactored it
and moved it into the correct package then everything worked! So it
was not a bug in Hibernate, just an informative exception that made it
difficult to track this issue down (I basically solved it by complete
fluke).

Hope this helps somebody, but in my case it was a problem with a wrong instrumentation.
I have class 'A' and two child classes 'B' and 'C'. 'A' class has a lazy property and it is instrumented to make the lazy accessing works.
But the mistake was that I didn't instrument the child classes 'B' and 'C', therefore any access to the instrumented property from 'B' and 'C' caused the exception.
When I instrumented 'B' and 'C', the problem went away.

Hibernate #CollectionOfElements and #Parent

I've done the following mapping:
#Entity
#Table(name = "NWS_NEWS")
public class News implements Serializable {
private static final long serialVersionUID = 5246618151933389186L;
private String id;
private List<Picture> pictures;
+ OTHER fields / getters / setters, no matter
#Id
#GeneratedValue(generator = "juuid")
#Column(length = 36)
public String getId() {
return id;
}
#CollectionOfElements
#JoinTable(name = "NWS_PICTURES",joinColumns = #JoinColumn(name="NEWS_ID"))
#CollectionId(
columns= #Column(name="PICTURE_ID"),
type=#Type(type="long"),
generator="sequence")
public List<Picture> getPictures() {
return pictures;
}
public void setPictures(List<Picture> pictures) {
this.pictures = pictures;
}
}
And my picture is:
#Embeddable
public class Picture implements Serializable {
private static final long serialVersionUID = -1397366206984323622L;
private News news;
private String path;
private ImageSize imageSize;
#Parent
public News getNews() {
return this.news;
}
#Column(name = "path", nullable=false)
public String getPath() {
return path;
}
#Enumerated(EnumType.STRING)
#Column(name = "size", nullable=false)
public ImageSize getImageSize() {
return imageSize;
}
public void setImageSize(ImageSize imageSize) {
this.imageSize = imageSize;
}
public void setNews(News news) {
this.news = news;
}
public void setPath(String path) {
this.path = path;
}
}
And my dao test is:
#Test
public void testAddPicturesToNews() {
News newsToSave = new News();
// Create big picture
Picture pBig = new Picture();
pBig.setImageSize(ImageSize.BIG);
pBig.setPath("/tmp/blabla_big.jpg");
// Create medium picture
Picture pMedium = new Picture();
pMedium.setImageSize(ImageSize.MEDIUM);
pMedium.setPath("/tmp/blabla_med.jpg");
// Set the pictures in the news
List<Picture> picturesList = new ArrayList<Picture>();
picturesList.add(pBig);
picturesList.add(pMedium);
newsToSave.setPictures(picturesList);
// Save the news
this.newsDAO.saveOrUpdate(newsToSave);
String newsId = newsToSave.getId();
News newsLoaded = this.newsDAO.findById(newsId);
List<Picture> picturesLoaded = newsLoaded.getPictures();
for ( Picture pictureLoaded : picturesLoaded ) {
System.out.println(pictureLoaded.getPath());
System.out.println(pictureLoaded.getImageSize());
System.out.println(pictureLoaded.getNews());
System.out.println("\n");
}
}
But the output is:
/tmp/blabla_big.jpg
BIG
null
/tmp/blabla_med.jpg
MEDIUM
null
Actually i don't understand why getNews() returns null in the child entity entity, while it has the "#Parent" annotation. Am i doing something wrong?
Anyway the concept of getting the parent in a child entity seems a bit strange for me since what would happen if i do something like that:
News news1 = new News();
News news2 = new News();
List<Picture> picList = new ArrayList<Picture>();
Picture picture1 = new Picture();
picturesList.add(picture1);
picture1.setNews(news2);
news1.setPictures(picList);
this.newsDAO.saveOrUpdate(news1);
this.newsDAO.saveOrUpdate(news2);
What would happen since the same picture will be in news1 list, but also its parent was set to news2???
I think i'll do without that parent, i don't need that so much but it's just curiosity...
Thanks
Btw i'd like to have only one picture of each size for a news -> there can't be 2 small pictures for the same news.
So is it possible to add a unique constraint on {news_id , imageSize} in my embedded entity? I don't see how to do that since no id field is declared in my Picture embeddable entity

I'm not familiar with the #Parent annotation for an #Embeddable, but for "real" relationships it's always recommended to do something like this:
// News class
public void setPictures(List<Picture> pictures) {
this.pictures = pictures;
for (Picture picture : pictures) {
picture.setNews(this);
}
}
public void addPicture(Picture picture) {
this.pictures.add(picture);
picture.setNews(this);
}
Remember that OOP, as opposed to the relational model, has only the notion of a "one-way" navigation, and that you should build the "two-way" by yourself. Encapsulating this behavior in the setter makes this transparent to your consumers. So, I'm not sure why your #Parent is not working, but I would try to do the opposite:
// what you have:
newsToSave.setPictures(picturesList);
// what I'd try:
pMedium.setNews(newsToSave);
What would happen since the same picture will be in news1 list, but also its parent was set to news2???
Well, an #Embeddable is an object which is "embedded" into another, meaning that it belongs only to that other object (parent). As such, it should contain only one parent. If you change the parent, it'll belong only to this new parent. If you need an object (Picture) to have a relationship with other objects (News), you'll need a #ManyToMany (if the other object, News, may also be linked to several Picture)