I have the following entities:
public class Parent implements Serializable {
#Id
private Long propertyId;
#OneToMany(mappedBy = "parent", orphanRemoval = true, cascade = CascadeType.ALL)
private List<Child> objects = new ArrayList<>();
And the child class:
public class Child implements Serializable {
#Id
#NotNull
private Long childId;
#Id
#JoinColumn(name = "parent_id")
#ManyToOne(fetch = FetchType.LAZY)
private Parent parent;
I am getting the data from a another api in csv file, parsing it and persisting it.
The way I persist the data is:
First creating the Parent objects from the csv file
Creating the Child objects from the csv file
Set for every Parent the list of children and for every children set the parent
In the end I have the following code that persists the data:
parentRepository.saveAll(parents);
where parents is the complete list where I have the complete data.
I am calling this api from time to time, which means every time is called there might be new data or the same but in the end I must persist it.
What is my question is how to track how many new records are added and how many records are updated. I know that I can do some filter thing and query every entity and check if it exists but since I have around 80 000 entites adding so many queries is really time consuming.
Any proposal of how to do this but not to be so time consuming? Is there any kind of interceptor that will maybe give me the data at the end of the query?
Some background:
When you use manually assigned ids, If the object you are sending already exists, hibernate does not issue insert or update.
The reason for this is that whenever you call save() on entities with manually assigned ids, hibernate first does a select to decide if it is insert or update.
But since it has already done a select, it can compare it to decide if they are exactly equal, in that case, it will not issue insert or update
You can verify this behaviour by adding spring.jpa.show-sql=true, spring.jpa.properties.hibernate.format_sql=true and
logging.level.org.hibernate.SQL=DEBUG to application.properties
Solution
Add the following fields and methods to your entity
#Transient
private boolean updated;
#Transient
private boolean created;
#PrePersist
public void setCreated() {
this.created = true;
}
#PreUpdate
public void setUpdated() {
this.updated = true;
}
public boolean isCreated() {
return created;
}
public boolean isUpdated() {
return updated;
}
After saveAll() ,
parent.isCreated() is true, then you know it is new insert
parent.isUpdated() is true, then you know it is update
If both are false, then insert or update didn't happen
I got a Deal which can have multiple DealItems.
The DealItems are linked in the Deal with the following JPA annotation:
public class DealEntity extends BasicEntity {
#OneToMany(mappedBy = "deal", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private List<DealItemEntity> items;
...
This is the relation inside a DealItem:
public class DealItemEntity extends BasicEntity {
#ManyToOne
#JoinColumn(name = "deal_id", nullable = false)
private DealEntity deal;
...
When I delete a DealItem it is deleted and persited again, when when I access the Deal after the deletion, see here:
public FullDealResponse deleteDealItem(final String dealCode, final long dealItemId) {
DealEntity dealEntity = dealControl.findDealByDealCode(dealCode);
if (dealEntity == null) {
throw new WorkbenchGenericErrorException("Deal not found");
}
DealItemEntity dealItemEntity = dealItemControl.findDealItemByIdAndDealId(dealItemId, dealEntity.getId());
if (dealItemEntity == null) {
throw new WorkbenchGenericErrorException("Deal item not found");
}
// this makes a database DELETE call that is executed after the session is done
dealItemControl.deleteDealItem(dealItemEntity);
// When I remove this and I do not return anything, the deletion works
return this.getFullDealResponse(dealEntity);
}
EDIT:
This is getFullDealResponse() and getFullDealItemResponse():
private FullDealResponse getFullDealResponse(final DealEntity dealEntity) {
FullDealResponse response = new FullDealResponse();
response.setDescription(dealEntity.getDescription());
response.setTitle(dealEntity.getTitle());
response.setDealCode(dealEntity.getDealCode());
response.setCreatedAt(dealEntity.getCreatedAt());
response.setUpdatedAt(dealEntity.getUpdatedAt());
// get related items
List<FullDealItemResponse> itemsResponse = new ArrayList<FullDealItemResponse>();
for (DealItemEntity dealItemEntity : dealEntity.getItems()) {
itemsResponse.add(this.getFullDealItemResponse(dealItemEntity));
}
response.setItems(itemsResponse);
return response;
}
private FullDealItemResponse getFullDealItemResponse(final DealItemEntity dealItemEntity) {
FullDealItemResponse response = new FullDealItemResponse();
response.setId(dealItemEntity.getId());
response.setDescription(dealItemEntity.getDescription());
response.setTitle(dealItemEntity.getTitle());
response.setCreatedAt(dealItemEntity.getCreatedAt());
response.setUpdatedAt(dealItemEntity.getUpdatedAt());
return response;
}
This is deleteDealItem() and delete() function:
public void deleteDealItem(final DealItemEntity dealItemEntity) {
super.delete(DealItemEntity.class, dealItemEntity.getId());
}
protected void delete(final Class<?> type, final Object id) {
Object ref = this.em.getReference(type, id);
this.em.remove(ref);
}
Can this be solved when I switch the CascadeType, and if so, which would be the correct type? Or would I have to iterate over Deal.getItems(), remove the unwanted item, set the new list with Deal.setItems() and update only the Deal so it propagates the deletion?
What is the preferred way to do this?
I have replicated this code locally and verified my explanation
Summary:
Cascade does not have impact. Even if you remove your cascade operation, save each item separately , then when you come to this method, it will not delete your item.
To have same behaviour regardless of deal.getItems initialisation, You will have to delete the dealItem by removing it from deal.getItems in addition to deleting the dealItem directly.
On a bi-directional relationship, you will have to explicitly manage both sides. Exactly the same way, you add the dealItem to deal as well set deal field of dealItem before you save.
Overall Explanation
JPA can have only one representation of a particular item associated with it's session.
It is the foundation for providing Repeatble Read, Dirty Checking etc.
JPA also tracks every object associated with its session and If any of the tracked objects have changes, they will flushed when the transaction committed.
When only deal object (with lazy deaItems collection) and the directly fetched dealItem are the only two entities associated with the session, then JPA has one presentation for each in the session, since there is no conflict, when you delete it, it deletes it via dealItemControl.deleteDealItem the dealItem is deleted
However, once you call deal.getItems, JPA not only manages deal, but also every dealItem associated with the deal object. So when when you delete the dealItemControl.deleteDealItem, JPA has an issue because deal.getItems tells it is not marked for delete. So the delete is not issued.
Reference: JPA QL generated also confirms my explanation
1. With deal.getItems and Queries Generated
#OneToMany(mappedBy = "deal", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private List<DealItemEntity> items;
DealEntity dealEntity = dealControl.findDealByDealCode(dealCode);
....
dealItemControl.deleteDealItem(dealItemEntity);
....
dealEntity.getItems()
select deal0_.* from deal deal0_ where deal0_.id=?
select dealitem0_.*
deal1_.*
from
deal_item dealitem0_ inner join deal deal1_ on dealitem0_.deal_id=deal1_.id
where
dealitem0_.id=?
select items0_.* from deal_item items0_ where items0_.deal_id=?
2. Without deal.getItems and Queries Generated
#OneToMany(mappedBy = "deal", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private List<DealItemEntity> items;
DealEntity dealEntity = dealControl.findDealByDealCode(dealCode);
....
dealItemControl.deleteDealItem(dealItemEntity);
select deal0_.* from deal deal0_ where deal0_.id=?
select dealitem0_.*
deal1_.*
from
deal_item dealitem0_ inner join deal deal1_ on dealitem0_.deal_id=deal1_.id
where
dealitem0_.id=?
delete from deal_item where id=?
I receive following error when I save the object using Hibernate
object references an unsaved transient instance - save the transient instance before flushing
You should include cascade="all" (if using xml) or cascade=CascadeType.ALL (if using annotations) on your collection mapping.
This happens because you have a collection in your entity, and that collection has one or more items which are not present in the database. By specifying the above options you tell hibernate to save them to the database when saving their parent.
I believe this might be just repeat answer, but just to clarify, I got this on a #OneToOne mapping as well as a #OneToMany. In both cases, it was the fact that the Child object I was adding to the Parent wasn't saved in the database yet. So when I added the Child to the Parent, then saved the Parent, Hibernate would toss the "object references an unsaved transient instance - save the transient instance before flushing" message when saving the Parent.
Adding in the cascade = {CascadeType.ALL} on the Parent's reference to the Child solved the problem in both cases. This saved the Child and the Parent.
Sorry for any repeat answers, just wanted to further clarify for folks.
#OneToOne(cascade = {CascadeType.ALL})
#JoinColumn(name = "performancelog_id")
public PerformanceLog getPerformanceLog() {
return performanceLog;
}
Introduction
When using JPA and Hibernate, an entity can be in one of the following 4 states:
New - A newly created object that hasn’t ever been associated with a Hibernate Session (a.k.a Persistence Context) and is not mapped to any database table row is considered to be in the New or Transient state.
To become persisted we need to either explicitly call the persist method or make use of the transitive persistence mechanism.
Persistent - A persistent entity has been associated with a database table row and it’s being managed by the currently running Persistence Context.
Any change made to such an entity is going to be detected and propagated to the database (during the Session flush-time).
Detached - Once the currently running Persistence Context is closed all the previously managed entities become detached. Successive changes will no longer be tracked and no automatic database synchronization is going to happen.
Removed - Although JPA demands that managed entities only are allowed to be removed, Hibernate can also delete detached entities (but only through a remove method call).
Entity state transitions
To move an entity from one state to the other, you can use the persist, remove or merge methods.
Fixing the problem
The issue you are describing in your question:
object references an unsaved transient instance - save the transient instance before flushing
is caused by associating an entity in the state of New to an entity that's in the state of Managed.
This can happen when you are associating a child entity to a one-to-many collection in the parent entity, and the collection does not cascade the entity state transitions.
So, you can fix this by adding cascade to the entity association that triggered this failure, as follows:
The #OneToOne association
#OneToOne(
mappedBy = "post",
orphanRemoval = true,
cascade = CascadeType.ALL)
private PostDetails details;
Notice the CascadeType.ALL value we added for the cascade attribute.
The #OneToMany association
#OneToMany(
mappedBy = "post",
orphanRemoval = true,
cascade = CascadeType.ALL)
private List<Comment> comments = new ArrayList<>();
Again, the CascadeType.ALL is suitable for the bidirectional #OneToMany associations.
Now, in order for the cascade to work properly in a bidirectional, you also need to make sure that the parent and child associations are in sync.
The #ManyToMany association
#ManyToMany(
mappedBy = "authors",
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
}
)
private List<Book> books = new ArrayList<>();
In a #ManyToMany association, you cannot use CascadeType.ALL or orphanRemoval as this will propagate the delete entity state transition from one parent to another parent entity.
Therefore, for #ManyToMany associations, you usually cascade the CascadeType.PERSIST or CascadeType.MERGE operations. Alternatively, you can expand that to DETACH or REFRESH.
This happens when saving an object when Hibernate thinks it needs to save an object that is associated with the one you are saving.
I had this problem and did not want to save changes to the referenced object so I wanted the cascade type to be NONE.
The trick is to ensure that the ID and VERSION in the referenced object is set so that Hibernate does not think that the referenced object is a new object that needs saving. This worked for me.
Look through all of the relationships in the class you are saving to work out the associated objects (and the associated objects of the associated objects) and ensure that the ID and VERSION is set in all objects of the object tree.
Or, if you want to use minimal "powers" (e.g. if you don't want a cascade delete) to achieve what you want, use
import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
...
#Cascade({CascadeType.SAVE_UPDATE})
private Set<Child> children;
In my case it was caused by not having CascadeType on the #ManyToOne side of the bidirectional relationship. To be more precise, I had CascadeType.ALL on #OneToMany side and did not have it on #ManyToOne. Adding CascadeType.ALL to #ManyToOne resolved the issue.
One-to-many side:
#OneToMany(cascade = CascadeType.ALL, mappedBy="globalConfig", orphanRemoval = true)
private Set<GlobalConfigScope>gcScopeSet;
Many-to-one side (caused the problem)
#ManyToOne
#JoinColumn(name="global_config_id")
private GlobalConfig globalConfig;
Many-to-one (fixed by adding CascadeType.PERSIST)
#ManyToOne(cascade = CascadeType.PERSIST)
#JoinColumn(name="global_config_id")
private GlobalConfig globalConfig;
This occurred for me when persisting an entity in which the existing record in the database had a NULL value for the field annotated with #Version (for optimistic locking). Updating the NULL value to 0 in the database corrected this.
This isn't the only reason for the error. I encountered it just now for a typo error in my coding, which I believe, set a value of an entity which was already saved.
X x2 = new X();
x.setXid(memberid); // Error happened here - x was a previous global entity I created earlier
Y.setX(x2);
I spotted the error by finding exactly which variable caused the error (in this case String xid). I used a catch around the whole block of code that saved the entity and printed the traces.
{
code block that performed the operation
} catch (Exception e) {
e.printStackTrace(); // put a break-point here and inspect the 'e'
return ERROR;
}
Don't use Cascade.All until you really have to. Role and Permission have bidirectional manyToMany relation. Then the following code would work fine
Permission p = new Permission();
p.setName("help");
Permission p2 = new Permission();
p2.setName("self_info");
p = (Permission)crudRepository.save(p); // returned p has id filled in.
p2 = (Permission)crudRepository.save(p2); // so does p2.
Role role = new Role();
role.setAvailable(true);
role.setDescription("a test role");
role.setRole("admin");
List<Permission> pList = new ArrayList<Permission>();
pList.add(p);
pList.add(p2);
role.setPermissions(pList);
crudRepository.save(role);
while if the object is just a "new" one, then it would throw the same error.
beside all other good answers, this could happen if you use merge to persist an object and accidentally forget to use merged reference of the object in the parent class. consider the following example
merge(A);
B.setA(A);
persist(B);
In this case, you merge A but forget to use merged object of A. to solve the problem you must rewrite the code like this.
A=merge(A);//difference is here
B.setA(A);
persist(B);
If your collection is nullable just try: object.SetYouColection(null);
This issue happened to me when I created a new entity and an associated entity in a method marked as #Transactional, then performed a query before saving. Ex
#Transactional
public someService() {
Entity someEntity = new Entity();
AssocaiatedEntity associatedEntity = new AssocaitedEntity();
someEntity.setAssociatedEntity(associatedEntity);
associatedEntity.setEntity(someEntity);
// Performing any query was causing hibernate to attempt to persist the new entity. It would then throw an exception
someDao.getSomething();
entityDao.create(someEntity);
}
To fix, I performed the query before creating the new entity.
To add my 2 cents, I got this same issue when I m accidentally sending null as the ID. Below code depicts my scenario (and OP didn't mention any specific scenario).
Employee emp = new Employee();
emp.setDept(new Dept(deptId)); // --> when deptId PKID is null, same error will be thrown
// calls to other setters...
em.persist(emp);
Here I m setting the existing department id to a new employee instance without actually getting the department entity first, as I don't want to another select query to fire.
In some scenarios, deptId PKID is coming as null from calling method and I m getting the same error.
So, watch for null values for PK ID
It can also happen when you are having OneToMany relation and you try to add the child entity to the list in parent entity, then retrieve this list through parent entity (before saving this parent entity), without saving child entity itself, e.g.:
Child childEntity = new Child();
parentEntity.addChild(childEntity);
parentEntity.getChildren(); // I needed the retrieval for logging, but one may need it for other reasons.
parentRepository.save(parentEntity);
The error was thrown when I saved the parent entity. If I removed the retrieval in the previous row, then the error was not thrown, but of course that's not the solution.
The solution was saving the childEntity and adding that saved child entity to the parent entity, like this:
Child childEntity = new Child();
Child savedChildEntity = childRepository.save(childEntity);
parentEntity.addChild(savedChildEntity);
parentEntity.getChildren();
parentRepository.save(parentEntity);
If you're using Spring Data JPA then addition #Transactional annotation to your service implementation would solve the issue.
I also faced the same situation. By setting following annotation above the property made it solve the exception prompted.
The Exception I faced.
Exception in thread "main" java.lang.IllegalStateException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.model.Car_OneToMany
To overcome, the annotation I used.
#OneToMany(cascade = {CascadeType.ALL})
#Column(name = "ListOfCarsDrivenByDriver")
private List<Car_OneToMany> listOfCarsBeingDriven = new ArrayList<Car_OneToMany>();
What made Hibernate throw the exception:
This exception is thrown at your console because the child object I attach to the parent object is not present in the database at that moment.
By providing #OneToMany(cascade = {CascadeType.ALL}) , it tells Hibernate to save them to the database while saving the parent object.
i get this error when i use
getSession().save(object)
but it works with no problem when I use
getSession().saveOrUpdate(object)
For the sake of completeness: A
org.hibernate.TransientPropertyValueException
with message
object references an unsaved transient instance - save the transient instance before flushing
will also occur when you try to persist / merge an entity with a reference to another entity which happens to be detached.
One other possible reason: in my case, I was attempting to save the child before saving the parent, on a brand new entity.
The code was something like this in a User.java model:
this.lastName = lastName;
this.isAdmin = isAdmin;
this.accountStatus = "Active";
this.setNewPassword(password);
this.timeJoin = new Date();
create();
The setNewPassword() method creates a PasswordHistory record and adds it to the history collection in User. Since the create() statement hadn't been executed yet for the parent, it was trying to save to a collection of an entity that hadn't yet been created. All I had to do to fix it was to move the setNewPassword() call after the call to create().
this.lastName = lastName;
this.isAdmin = isAdmin;
this.accountStatus = "Active";
this.timeJoin = new Date();
create();
this.setNewPassword(password);
There is another possibility that can cause this error in hibernate. You may set an unsaved reference of your object A to an attached entity B and want to persist object C. Even in this case, you will get the aforementioned error.
There are so many possibilities of this error some other possibilities are also on add page or edit page. In my case I was trying to save a object AdvanceSalary. The problem is that in edit the AdvanceSalary employee.employee_id is null Because on edit I was not set the employee.employee_id. I have make a hidden field and set it. my code working absolutely fine.
#Entity(name = "ic_advance_salary")
#Table(name = "ic_advance_salary")
public class AdvanceSalary extends BaseDO{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "employee_id", nullable = false)
private Employee employee;
#Column(name = "employee_id", insertable=false, updatable=false)
#NotNull(message="Please enter employee Id")
private Long employee_id;
#Column(name = "advance_date")
#DateTimeFormat(pattern = "dd-MMM-yyyy")
#NotNull(message="Please enter advance date")
private Date advance_date;
#Column(name = "amount")
#NotNull(message="Please enter Paid Amount")
private Double amount;
#Column(name = "cheque_date")
#DateTimeFormat(pattern = "dd-MMM-yyyy")
private Date cheque_date;
#Column(name = "cheque_no")
private String cheque_no;
#Column(name = "remarks")
private String remarks;
public AdvanceSalary() {
}
public AdvanceSalary(Integer advance_salary_id) {
this.id = advance_salary_id;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Employee getEmployee() {
return employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
public Long getEmployee_id() {
return employee_id;
}
public void setEmployee_id(Long employee_id) {
this.employee_id = employee_id;
}
}
I think is because you have try to persist an object that have a reference to another object that is not persist yet, and so it try in the "DB side" to put a reference to a row that not exists
Case 1:
I was getting this exception when I was trying to create a parent and saving that parent reference to its child and then some other DELETE/UPDATE query(JPQL). So I just flush() the newly created entity after creating parent and after creating child using same parent reference. It Worked for me.
Case 2:
Parent class
public class Reference implements Serializable {
#Id
#Column(precision=20, scale=0)
private BigInteger id;
#Temporal(TemporalType.TIMESTAMP)
private Date modifiedOn;
#OneToOne(mappedBy="reference")
private ReferenceAdditionalDetails refAddDetails;
.
.
.
}
Child Class:
public class ReferenceAdditionalDetails implements Serializable{
private static final long serialVersionUID = 1L;
#Id
#OneToOne
#JoinColumn(name="reference",referencedColumnName="id")
private Reference reference;
private String preferedSector1;
private String preferedSector2;
.
.
}
In the above case where parent(Reference) and child(ReferenceAdditionalDetails) having OneToOne relationship and when you try to create Reference entity and then its child(ReferenceAdditionalDetails), it will give you the same exception. So to avoid the exception you have to set null for child class and then create the parent.(Sample Code)
.
.
reference.setRefAddDetails(null);
reference = referenceDao.create(reference);
entityManager.flush();
.
.
In my case , issue was completely different. I have two classes let's say c1 & c2. Between C1 & C2 dependency is OneToMany. Now if i am saving C1 in DB it was throwing above error.
Resolution of this problem was to get first C2's id from consumer request and find C2 via repository call.Afterwards save c2 into C1 object .Now if i am saving C1, it's working fine.
I was facing the same error for all PUT HTTP transactions, after introducing optimistic locking (#Version)
At the time of updating an entity it is mandatory to send id and version of that entity. If any of the entity fields are related to other entities then for that field also we should provide id and version values, without that the JPA try to persist that related entity first as a new entity
Example: we have two entities --> Vehicle(id,Car,version) ; Car(id, version, brand); to update/persist Vehicle entity make sure the Car field in vehicle entity has id and version fields provided
Simple way of solving this issue is save the both entity.
first save the child entity and then save the parent entity.
Because parent entity is depend on child entity for the foreign key value.
Below simple exam of one to one relationship
insert into Department (name, numOfemp, Depno) values (?, ?, ?)
Hibernate: insert into Employee (SSN, dep_Depno, firstName, lastName, middleName, empno) values (?, ?, ?, ?, ?, ?)
Session session=sf.openSession();
session.beginTransaction();
session.save(dep);
session.save(emp);
One possible cause of the error is the inexistence of the setting of the value of the parent entity ; for example for a department-employees relationship you have to write this in order to fix the error :
Department dept = (Department)session.load(Department.class, dept_code); // dept_code is from the jsp form which you get in the controller with #RequestParam String department
employee.setDepartment(dept);
I faced this exception when I did not persist parent object but I was saving the child. To resolve the issue, with in the same session I persisted both the child and parent objects and used CascadeType.ALL on the parent.
My problem was related to #BeforeEach of JUnit. And even if I saved the related entities (in my case #ManyToOne), I got the same error.
The problem is somehow related to the sequence that I have in my parent.
If I assign the value to that attribute, the problem is solved.
Ex.
If I have the entity Question that can have some categories (one or more) and entity Question has a sequence:
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "feedbackSeq")
#Id
private Long id;
I have to assign the value question.setId(1L);
Just make Constructor of your mapping in your base class.
Like if you want One-To-One relation in Entity A, Entity B.
if your are taking A as base class, then A must have a Constructor have B as a argument.
How do get the object I want, without all of the child associations.
I have my class Site:
#Entity
#Table(name = "Sites")
public class Site {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "Id_Site", unique = true, nullable = false)
private long Id_Site;
private String ...;
private boolean ...;
private long ...;
private Date ...;
private Date ...;
private String ...;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Set<Sequence> sequences = new HashSet<>();
#ManyToOne
private ... ...;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Set<...> ... = new HashSet<>();
#ManyToOne
private ... ...;
public constructor...
public set..
public get..
}
I only need a Site object, without the Sequence Associations.
In my Sequence Table, I have:
#Entity
#Table(name = "Sequences")
public class Sequence {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "Id_Sequence", unique = true, nullable = false)
private long Id_Sequence;
private Date ....;
private Date ....;
private String ....;
private String ....;
private String ....;
private int ....;
private int ....;
private double ....;
private double ....;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<TraceSequence> traceSequences = new HashSet<>();
#ManyToOne(cascade = CascadeType.ALL)
private Site site;
public constructor...
public set..
public get..
}
When I use FetchType.Lazy, and call my method:
#Override
public Site findSiteByName(String Name_Site) {
List<Site> sites = entityManager.createQuery("SELECT s FROM Site s").getResultList();
for (Site item : sites) {
if (item.getNom_Site().equals(Name_Site)) {
return item;
}
}
return null;
}
I get this error:
failed to lazily initialize a collection of role: xxx.xxx.xxx.xxx.xxx.site.Site.sequences, could not initialize proxy - no Session
When I use FetchType.EAGER, I get not only a Site object, but I also get all sequence objects, and all objects of other sequence associations. (I know it is the normal response.)
Could someone who knows why this attempt at lazy initialization doesn't work, please, tell me how to resolve this problem.
These lazy errors happens when the jpa tries to get the data after the session is closed.
But using eager will influence all the queries that include that entity.
Try to use a join fetch in the query instead of the eager.
Somewhere in your code you are calling Site.GetSequences(), maybe iterating in the view or in another part of your code. It doesn't look like the piece of code you gave are generating the exception.
I you try to use a collection that is not loaded to your entity, the code throws the exception you mentioned.
To solve this, identify where you are using the sequences and load them before you use by changing the fetch to EAGER or using the JOIN FETCH in your query.
Returning a hibernate managed entity (or a collection of hibernate managed entities) will most likely cause these sort of problems unless you are super cautious on what is being returned and what was populated by hibernate when session was available.
I would say create a DTO (or a collection of DTO) and populate its fields the way you like. There are many Entity to DTO conversion framework; my fav is ModelMapper.
I also tend to agree with other suggestions to play with FetchType but since DTOs are populated by us we know what we populated as opposed to entity-relationships which are populated by hibernate based on annotations.
If you need something in the DTO you simply ask the entity and since session would be available at that point of time you could populate any field that you think you would need on the UI.
I don't want to hijack this topic towards DTO and Entity but that's how I would do it.
This may be helpful too Avoid Jackson serialization on non fetched lazy objects
Error happen becouse you try execute getSequences(), but becouse of is lazy and session is alredy closed hibernate rais the error.
To avoid this error read read sequencese inside query method, "inside" session, like this:
public Site findSiteByName(String Name_Site) {
List sites = entityManager.createQuery("SELECT s FROM Sites").getResultList();
for (Site item : sites) {
if (item.getNom_Site().equals(Name_Site)) {
item.getSites();
return item;
}
}
return null;
}
This is a lazy loading, you read collenction just when you need it!
As stated by other SE members above, you are getting this error because session is already closed.
If you want to load a particular object then you can use Hibernate.initialize method. it will execute one additional query to fetch the data of related entity.
Therefore, it is as per need basis and will not be executed all times as compared to Eager loading
I'm working on a project that aims to solve common JPA problems when mapping entities to DTOs using ModelMapper. This issue has already been solved on the project. Project link: JPA Model Mapper
On this scenario I believe that we'd want to simply get null for all lazy load entities. For this question specifically, this could be done by using de JPA Model Mapper to map an entity to DTO.
I've already answered the same issue on this question: How to solve the LazyInitializationException when using JPA and Hibernate
I have following classes:
Company.class:
public class Company {
#JoinTable(name = "company_employee", joinColumns = #JoinColumn(name = "company_id") , inverseJoinColumns = #JoinColumn(name = "employee_id") )
#ManyToMany(fetch = FetchType.LAZY)
private Set<Employee> employees;
#Column(name = "score")
private BigDecimal score;
}
and Employee.class
public class Employee {
#ManyToMany(fetch = FetchType.EAGER, mappedBy="employees")
private Set<Company> companies;
}
The Score column of Company is always null in the db and never updated via dao, because there is other table containing score for each unique pair Company-Employee.
I need the value of Score, only for the case when I fetch Employee by id, so this case all Company instances in the Set should contain score, thus I will get Employee-Company score pairs where employee is fetched Employee.
I have following code to achieve that:
public Employee get(Long id) {
Employee emp = (Employee) dao.find(id);
List<Company> compList = compnanyService.getByEmpId(id);
Set<Company> compSet = new HashSet<Company>(compList);
emp.setCompanies(compSet);
return emp;
}
And Company Dao contains method:
public List<Company> getByEmpId(Long id) {
final Query query = this.entityManager.createNativeQuery("select company.comp_id, ...some other fields, score.score from company join score on company.company_id=score.company_id where score.employee_id=:employee_id",
Company.class);
query.setParameter("employee_id", id);
List<Company> comps = query.getResultList();
return comps;
}
The problem is that getByEmpId(id) gives a ResultList where company.score is null though executed in the db it is not null.
I suspected that there is some caching intervening, so I tried to remove some columns from the native query, and it should have invoked an exception with "no column found" (or alike) message while mapping, but this method still gives List<Company> with all fields on their places though Hibernate prints out my native query in the console with all changes I make.
What am I doing wrong here and how to achieve what I need? Thank you.
It might be associated with first level cache, which can be out of sync when using native SQL queries. From here:
If you bypass JPA and execute DML directly on the database, either
through native SQL queries, JDBC, or JPQL UPDATE or DELETE queries,
then the database can be out of synch with the 1st level cache. If you
had accessed objects before executing the DML, they will have the old
state and not include the changes. Depending on what you are doing
this may be ok, otherwise you may want to refresh the affected objects
from the database.
So you can try using refresh method from EntityManager.
So I ended up doing that:
Created view in db from the query:
CREATE VIEW companyscore AS select company.comp_id, score.emp_id ...some other fields, score.score from company join score on company.comp_id=score.comp_id;
Created corresponding entity CompanyScore with composite primary id as comp_id and emp_id and created view as table.
Changed Employee entity to:
public class Employee {
#OneToMany(fetch = FetchType.EAGER)
#JoinColumn(name = "emp_id")
private Set<CompanyScore> companies;
}
This way I not only have score field always consistent, but I can choose set of fields to show as the whole Company class is quite extensive and I don't need all the fields for this particular case.