JPA not saving foreign key to #OneToMany relation - java

I'm using Spring with Hibernate as a JPA provider and are trying to get a #OneToMany (a contact having many phonenumbers) to save the foreign key in the phone numbers table. From my form i get a Contact object that have a list of Phone(numbers) in it. The Contact get persisted properly (Hibernate fetches an PK from the specified sequence). The list of Phone(numbers) also gets persisted with a correct PK, but there's no FK to the Contacts table.
public class Contact implements Serializable {
#OneToMany(mappedBy = "contactId", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
private List<Phone> phoneList;
}
public class Phone implements Serializable {
#JoinColumn(name = "contact_id", referencedColumnName = "contact_id")
#ManyToOne
private Contact contactId;
}
#Repository("contactDao")
#Transactional(readOnly = true)
public class ContactDaoImpl implements ContactDao {
#Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW)
public void save(Contact c) {
em.persist(c);
em.flush();
}
}
#Controller
public class ContactController {
#RequestMapping(value = "/contact/new", method = RequestMethod.POST)
public ModelAndView newContact(Contact c) {
ModelAndView mv = new ModelAndView("contactForm");
contactDao.save(c);
mv.addObject("contact", c);
return mv;
}
}
Hopefully I got all of the relevant bits above, otherwise please let me know.


You have to manage the Java relationships yourself. For this kind of thing you need something like:
#Entity
public class Contact {
#Id
private Long id;
#OneToMany(cascade = CascadeType.PERSIST, mappedBy = "contact")
private List<Phone> phoneNumbers;
public void addPhone(PhoneNumber phone) {
if (phone != null) {
if (phoneNumbers == null) {
phoneNumbers = new ArrayList<Phone>();
}
phoneNumbers.add(phone);
phone.setContact(this);
}
}
...
}
#Entity
public class Phone {
#Id
private Long id;
#ManyToOne
private Contact contact;
...
}


In reply to Cletus' answer. I would say that it's important to have the #column annotation on the id fields, as well as all the sequence stuff. An alternative to using the mappedBy parameter of the #OneToMany annotation is to use the #JoinColumn annotation.
As a kinda aside your implementation of addPhone needs looking at. It should probably be something like.
public void addPhone(PhoneNumber phone) {
if (phone == null) {
return;
} else {
if (phoneNumbers == null) {
phoneNumbers = new ArrayList<Phone>();
}
phoneNumbers.add(phone);
phone.setContact(this);
}
}


If the Contact-Phone relationship is unidirectional, you can also replace mappedBy in #OneToMany annotation with #JoinColumn(name = "contact_id").
#Entity
public class Contact {
#Id
private Long id;
#OneToMany(cascade = CascadeType.PERSIST)
#JoinColumn(name = "contact_id")
private List<Phone> phoneNumbers;
// normal getter/setter
...
}
#Entity
public class PhoneNumber {
#Id
private Long id;
...
}
Similar in JPA #OneToMany -> Parent - Child Reference (Foreign Key)


I don't think the addPhone method is necessary, you only have to set the contact in the phone object:
phone.setContact(contact);


If you want your relationship unidirectional i.e. can navigate from Contact to Phone's only, you need to add
#JoinColumn(name = "contact_id", nullable = false)
Under your #OneToMany on your parent entity.
nullable = false IS VITAL if you want hibernate to populate the fk on the child table


Try this sample:
#Entity
public class Contact {
#Id
private Long id;
#JoinColumn(name = "contactId")
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
private Set<Phone> phones;
}
#Entity
public class Phone {
#Id
private Long id;
private Long contactId;
}


In JPA this helped me
contact.getPhoneList().forEach(pl -> pl.setContact(contact));
contactRepository.save(contact);

Related

Hibernate insert null values ​in composite foreign key

I have two simple domain objects as follows:
USER:
#Entity
#Table(name="USER")
#IdClass(UserPK.class)
public class User implements Serializable {
//...
#Id
#Column(name = "FISCALCODE")
private String fiscalCode;
#Id
#Column(name = "USERNUMBER")
private String userNumber;
#OneToMany(mappedBy="user", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<Items> items;
// getters and setters
}
UserPK:
public class UserPK implements Serializable {
#Column(name = "FISCALCODE")
private String fiscalCode;
#Column(name = "USERNUMBER")
private String userNumber;
// getter and setter
}
ITEMS:
#Entity
#Table(name="ITEMS")
public class Items implements Serializable {
//...
#Id
#Column(name = "ID_ITEM")
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_item_generator")
#SequenceGenerator( name = "id_item_generator", sequenceName = "ITEM_SEQ", allocationSize = 1)
private Integer id;
#ManyToOne
#JoinColumns({
#JoinColumn(name="FISCALCODE"),
#JoinColumn(name="USERNUMBER")
})
private User user;
// getters and setters
}
DB Table:
user { fiscalcode, usernumber, other columns... } // fiscalcode+usernumber = PK
items { id, fiscalcode, usernumber, other columns... } // fiscalcode,usernumber is a foreign key
CONTROLLER:
#RequestMapping(value="/user", method = RequestMethod.POST, produces = "application/json")
public Object postUser(#RequestBody(required = false) User user){
//connection etc..
session.save(user);
//...
return new ResponseEntity<>(HttpStatus.OK);
}
Why when I run the command session.save(user) Hibernate insert value null in the columns FISCALCODE and USERNUMBER of the ITEMS table?
I tried to set the ManyToOne and the JoinColumns on the getter, but the result is the same.
EDIT: i have added my method for POST operation

As it's stated in the documentation for #JoinColumns:
When the JoinColumns annotation is used, both the name and the referencedColumnName elements must be specified in each such JoinColumn annotation.
So, you should correct your mapping like below:
#ManyToOne
#JoinColumns({
#JoinColumn(name="FISCALCODE", referencedColumnName = "FISCALCODE"),
#JoinColumn(name="USERNUMBER", referencedColumnName = "USERNUMBER")
})
private User user;
Whenever a bidirectional association is formed, the application developer must make sure both sides are in-sync at all times.
So, you should have in your User entity the addItem() and removeItem() utility methods that synchronize both ends whenever a child element is added or removed like below.
#Entity
#Table(name="USER")
#IdClass(UserPK.class)
public class User implements Serializable {
//...
#OneToMany(mappedBy="user", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<Items> items;
// getters and setters
public void addItem(Items item) {
this.items.add(item);
item.setUser(this);
}
public void removeItem(Items item) {
this.items.remove(item);
item.setUser(null);
}
}
Example of saving:
User user = new User();
user.setFiscalCode("Code1");
user.setUserNumber("User1");
// ...
Items item1 = new Items();
Items item2 = new Items();
// ...
user.addItem(item1);
user.addItem(item2);
session.save(user);

How to add data to Many to Many association with extra column using JPA, Hibernate

I have a User table and a Book table that I would like to connect.
So I created third table Borrow that has foreign key (book_id, user_id) and takenDate and broughtDate fields.
User.java
#Entity
#Table(name = "Users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String surname;
private String username;
private String email;
private String password;
#OneToMany(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
private List<Borrow> borrow;
....
Book.java
#Entity
#Table(name = "Books")
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String title;
private String ISBN;
private String author;
private String issuer;
private Integer dateOfIssue;
private Boolean IsRented;
#OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
private List<Borrow> borrow;
.....
Borrow.java
#Entity
#Table(name = "Borrows")
#IdClass(BorrowId.class)
public class Borrow {
private Date takenDate;
private Date broughtDate;
//lazy means it will get details of book
// only if we call GET method
#Id
#JsonIgnore
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "book_id", referencedColumnName = "id")
private Book book;
#Id
#JsonIgnore
#ManyToOne
#JoinColumn(name = "user_id", referencedColumnName = "id")
private User user;
....
BorowId.java
public class BorrowId implements Serializable {
private int book;
private int user;
// getters/setters and most importantly equals() and hashCode()
public int getBook() {
return book;
}
public void setBook(int book) {
this.book = book;
}
public int getUser() {
return user;
}
public void setUser(int user) {
this.user = user;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof BorrowId)) return false;
BorrowId borrowId = (BorrowId) o;
return getBook() == borrowId.getBook() &&
getUser() == borrowId.getUser();
}
#Override
public int hashCode() {
return Objects.hash(getBook(), getUser());
}
}
My MySql database design looks like this:
I am trying to add data to Borrow table something like this:
EDITED
#Transactional
#PostMapping("/addUser/{id}/borrow")
public ResponseEntity<Object> createItem(#PathVariable int id, #RequestBody Borrow borrow, #RequestBody Book book){
Optional<User> userOptional = userRepository.findById(id);
Optional<Book> bookOptional = bookRepository.findById(book.getId());
if(!userOptional.isPresent()){
throw new UserNotFoundException("id-" + id);
}
User user = userOptional.get();
borrow.setUser(user);
borrow.setBook(book);
borrowRepository.save(borrow);
URI location = ServletUriComponentsBuilder.fromCurrentRequest().path("/{id}").buildAndExpand(borrow.getId()).toUri();
return ResponseEntity.created(location).build();
}
I have't finished it because I am not sure how :/
Any tip is appreciated!

You are almost there. You just have to keep in mind two things:
1) You have to fetch the Book via repository as well (you only fetch the User currently)
2) All three operation have to be within the same transactional context:
fetching of `User`, fetching of `Book` and save `Borrow` entity.
TIP: You can put all these inside a Service and mark it as #Transactional or mark the #Post method as #Transactional. I would suggest first option, but it is up to you.
EDIT:
Optional<Book> bookOptional = bookRepository.findById(book.getId());
Also, it seems adequate to use #EmbeddedId instead of #IdClass here as ids are actual foreign entities:
#Embeddable
public class BorrowId{
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "book_id", referencedColumnName = "id")
private Book book;
#ManyToOne
#JoinColumn(name = "user_id", referencedColumnName = "id")
private User user;
}
and then in the Borrow class:
#Entity class Borrow{
#EmbeddedId BorrwId borrowId;
...
}
and in the Post method:
BorrowId borrowId = new BorrowId();
borrowId.setUser(user);
borrowId.setBook(book);
borrow.setBorrowId(borrowId);
borrowRepository.save(borrow);

JPA 1:N relationship removing child does not remove it from parent

I have the following objects:
#NoArgsConstructor
#AllArgsConstructor
#Getter
#Entity(name="Group")
public class Group {
#Id
#GeneratedValue
#NotNull
#Column(name = "GROUP_ID")
private Long id;
#Column(name="NAME")
private String name;
#OneToMany(
targetEntity = Product.class,
mappedBy = "groupId",
cascade = CascadeType.ALL,
fetch = FetchType.EAGER,
orphanRemoval = true
)
private List<Product> products = new ArrayList<>();
public Group(String name) {
this.name = name;
}
#Getter
#Setter
#AllArgsConstructor
#NoArgsConstructor
#Entity(name="Product")
public class Product {
#Id
#GeneratedValue
#NotNull
#Column(name="PRODUCT_ID")
private Long id;
#Column(name="NAME")
private String name;
#Column(name="DESCRIPTION")
private String description;
#Column(name="PRICE")
private double price;
#ManyToMany
#JoinTable(
name = "JOIN_PRODUCT_CART",
joinColumns = {#JoinColumn(name = "PRODUCT_ID", referencedColumnName = "PRODUCT_ID")},
inverseJoinColumns = {#JoinColumn(name = "CART_ID", referencedColumnName = "CART_ID")}
)
private List<CartEntity> carts = new ArrayList<>();
#ManyToOne
#JoinColumn(name = "GROUP_ID")
private Group groupId;
public Product(String name, String description, double price) {
this.name = name;
this.description = description;
this.price = price;
}
public Product(String name, String description, double price, Group groupId) {
this(name, description, price);
this.groupId = groupId;
}
public void addToCart(CartEntity cart) {
this.carts.add(cart);
cart.getProductsList().add(this);
}
public void addGroup(Group group) {
group.getProducts().add(this);
this.groupId = group;
}
#Getter
#NoArgsConstructor
#AllArgsConstructor
#Entity(name = "cart")
public class CartEntity {
#Id
#NotNull
#GeneratedValue
#Column(name = "CART_ID")
private Long id;
#ManyToMany(cascade = CascadeType.ALL, mappedBy = "carts")
private List<Product> productsList = new ArrayList<>();
public void addProduct(Product product) {
productsList.add(product);
product.getCarts().add(this);
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CartEntity that = (CartEntity) o;
return id.equals(that.id);
}
#Override
public int hashCode() {
return Objects.hash(id);
}
}
Now, when I have the following test:
public class ProductDaoTestSuite {
#Autowired
private ProductDao productDao;
#Autowired
private CartDaoStub cartDaoStub;
#Autowired
private GroupDao groupDao;
#Test
public void testDeleteProduct() {
// Given
Product product = new Product("test", "testProduct", 100.0);
Group group = new Group("group1");
CartEntity cart = new CartEntity();
product.addGroup(group);
cart.addProduct(product);
// When
groupDao.save(group);
productDao.save(product);
cartDaoStub.save(cart);
Long groupId = group.getId();
Long productId = product.getId();
Long cartId = cart.getId();
productDao.deleteById(productId);
// Then
Assert.assertTrue(cartDaoStub.findById(cartId).isPresent());
Assert.assertEquals(0, cartDaoStub.findById(cartId).get().getProductsList().size());
Assert.assertTrue(groupDao.findById(groupId).isPresent());
Assert.assertEquals(0, groupDao.findById(groupId).get().getProducts().size());
Following product deletion, I would expect association with it in group and cart to disappear (product to disappear from their List relationship fields). However, that is not happening at the moment. When I use Group/Cart Dao to pull group & cart from the DB after product deletion, they still have product in their Lists, while product when pulled from the DB is returned as null.
I have tried to add "orphanRemoval = true" value for #OneToMany adnotation, but it did not seem to work for Group entity.
What am I doing wrong?
I have started experimenting with adding all types of cascade (except for REMOVE) to #ManyToOne on Product class, but so far no luck.

For 1:N, yours should work just fine with minor adjustment.
The reason why it fails: Upon doing "groupDao.save(group);" this group is now in the persistence context and calling "groupDao.findById(groupId).get().getProducts().size()" would return the copy which is from the persistence context.
To solve this: simply add: entityManager.flush(); and entityManager.clear(); before the Assert
I would like to demonstrate it with this Integration Test
#Test
#Transactional
public void deleteProduct_groupShouldNowBeEmpty() {
ProductGroup group = groupRepository.findById("0001").orElseThrow(() -> new IllegalArgumentException("id not found"));
Assert.assertEquals(1, group.getProducts().size());
Product product = productRepository.findById("0001").orElseThrow(() -> new IllegalArgumentException("id not found"));
productRepository.delete(product);
entityManager.flush();
entityManager.clear();
Assert.assertEquals(0, productRepository.findAll().size());
Assert.assertEquals(0, groupRepository.findById("0001").get().getProducts().size());
}
If we are to remove the first 2 lines, then we won't need to flush and clear. Like this.
#Test
#Transactional
public void deleteProduct_groupShouldNowBeEmpty() {
Product product = productRepository.findById("0001").orElseThrow(() -> new IllegalArgumentException("id not found"));
productRepository.delete(product);
Assert.assertEquals(0, productRepository.findAll().size());
Assert.assertEquals(0, groupRepository.findById("0001").get().getProducts().size());
}
For N:M, since there would be another table where product is being referenced, then we would need to delete the records from that table first before deleting the product.
N:M is a bit tricky so if I can suggest domain changes, here how I'll do it. (The integration test is at the bottom.)
I'll add a separate entity: CartItem
which is associated to a Product and Cart
#Entity
public class CartItem {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "uuid2")
private String id;
#ManyToOne
private Product product;
#ManyToOne
private Cart cart;
public String getId() {
return id;
}
// Required by JPA
protected CartItem() {}
}
And for the Product Entity: add a bidirectional relationship with CartItem
#Entity
public class Product {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "uuid2")
private String id;
private String name;
private String description;
private BigDecimal price;
#ManyToOne
private ProductGroup group;
#OneToMany(mappedBy = "product")
private List<CartItem> cartItems;
public List<CartItem> getCartItems() {
return cartItems;
}
// Required by JPA
protected Product() {}
}
Then, retrieve the product (using Join Fetch to avoid N+1, since later will be looping through each cartItem)
public interface ProductRepository extends JpaRepository<Product, String> {
#Query("SELECT product FROM Product product JOIN FETCH product.cartItems")
Optional<Product> findProduct(String Id);
}
create another query inside CartItemRepository to delete cartItems in bulk by ids
public interface CartItemRepository extends JpaRepository<CartItem, String> {
#Modifying
#Query("DELETE FROM CartItem cartItem WHERE cartItem.id IN :ids")
void deleteByIds(#Param("ids") List<String> ids);
}
Lastly here's the integration test to wrap everthing up:
#Test
#Transactional
public void deleteProduct_associatedWithCart() {
Cart cart = cartRepository.findById("0001").get();
Assert.assertEquals(1, cart.getCartItems().size());
Product product = productRepository.findProduct("0001").orElseThrow(() -> new IllegalArgumentException("id not found"));
List<String> cartItemIds = product.getCartItems().stream()
.map(CartItem::getId)
.collect(Collectors.toList());
cartItemRepository.deleteByIds(cartItemIds);
productRepository.delete(product);
entityManager.flush();
entityManager.clear();
Assert.assertEquals(0, productRepository.findAll().size());
Assert.assertEquals(0, groupRepository.findById("0001").get().getProducts().size());
Assert.assertEquals(0, cartItemRepository.findAll().size());
Assert.assertEquals(0, cartRepository.findById("0001").get().getCartItems().size());
}
I've used DBUnit for this integration test so I think it would also be helpful to share the dataset.
<?xml version="1.0" encoding="UTF-8" ?>
<dataset>
<product_group id="0001" name="product group with 1 product"/>
<product id="0001" group_id="0001" />
<cart id="0001" />
<cart_item id="0001" product_id="0001" cart_id="0001" />
</dataset>

When you remove an entity, this state transition should be propagated from parent to child, not the other way around.
In this case, you need to move that functionally to the Group entity, something like this:
#NoArgsConstructor
#AllArgsConstructor
#Getter
#Entity(name="Group")
public class Group {
#Id
#GeneratedValue
#NotNull
#Column(name = "GROUP_ID")
private Long id;
#Column(name="NAME")
private String name;
#OneToMany(
targetEntity = Product.class,
mappedBy = "groupId",
cascade = CascadeType.ALL,
fetch = FetchType.LAZY, // Always prefer LAZY initialized Collections to EAGER ones
orphanRemoval = true
)
private List<Product> products = new ArrayList<>();
public Group(String name) {
this.name = name;
}
public void addProduct(Product product){
product.setGroupId(this);
this.products.add(product);
}
public void removeProduct(Product product){
product.setGroupId(null);
this.products.remove(product);
}
If you want to remove a Product, you only need to invoke the removeProduct method and save the parent entity:
Group group = new Group("group1");
Product product = new Product("test", "testProduct", 100.0);
group.addProduct(product);
groupDao.save(group);
On the other hand, we have the many-to-many relation between Product and CartEntity.
First, if you configure the entity CartEntity with Cascade.ALL as in your example:
#ManyToMany(cascade = CascadeType.ALL, mappedBy = "carts")
private List<Product> productsList = new ArrayList<>();
It will have a probably undesired effect: if you remove the CartEntity, it will remove all the Products associated with the entity as well, even if other CartEntitys are still associated to them. Vlad Mihalcea explain it in great detail in this article.
To avoid that problem, the best option will be just define the relationship as follows:
#ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = "carts")
private List<Product> productsList = new ArrayList<>();
This will give us a CartEntity like this:
#Getter
#NoArgsConstructor
#AllArgsConstructor
#Entity(name = "cart")
public class CartEntity {
#Id
#NotNull
#GeneratedValue
#Column(name = "CART_ID")
private Long id;
#ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = "carts")
private List<Product> productsList = new ArrayList<>();
public void addProduct(Product product) {
productsList.add(product);
product.getCarts().add(this);
}
public void removeProduct(Product product) {
productsList.remove(product);
product.getCarts().remove(this);
}
public void removeProducts() {
for(Product product : new ArrayList<>(products)) {
removeProduct(product);
}
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CartEntity that = (CartEntity) o;
return id.equals(that.id);
}
#Override
public int hashCode() {
return Objects.hash(id);
}
}
Please, note the inclusion of the removeProduct and removeProducts methods.
With this code, if you need to remove a CartEntity, just do the following:
cart.removeProducts();
cartDao.remove(cart);
And if you need to remove a Product from the CartEntity (will only remove the relation):
cart.removeProduct(product);
cartDao.save(cart);
If you need to propagate the Product remove to the CartEntity, I think that the best option will be create a business method that takes care of the whole process. Think in something like:
public void removeProduct(Product product){
Group group = product.getGroupId();
group.removeProduct(product);
final List<CartEntity> carts = product.getCarts();
if (carts != null) {
for(CartEntity cart : new ArrayList<>(carts)) {
cart.removeProduct(product);
cartDao.save(cart);
}
}
groupDao.save(group);
}

It will remove the association, you just need to do small adjustments.
1:N. When you remove Product, you don't have to do anything else in order to remove its association with Group, because the product itself holds the association (in DB column product.group_id). You just need to commit the transaction. And next time when you load a group from the DB it for sure will not contain this product.
N:M. There is no way to automatically remove the association because it is stored in a separate table and you don't have a separate entity for it. (YOU SHOULD NOT USE CascadeType.ALL for N:M relations). What you want to do is remove the association before you remove the product. Just add another helper method to Product.
public void removeFromCarts() {
carts.forEach(c -> c.getProducts().remove(this));
carts.clear();
}
So finally, in order to remove a product and all the associations with it. You will need to do the following:
product.removeFromCarts();
productDao.deleteById(productId); // not sure why you remove by id (not pass object)
*please note that you need to commit transaction and close the session. So you cannot rely on the test. In real app when you do what I described, it will work
**N:M is tricky. For instance, you should better use Set instead of List to avoid unexpected SQL under the hood. Also going down the road, I recommend you to consider splitting N:M into two N:1 and 1:M and have a dedicated Entity for a link table

Not sure I follow. Hibernate does not automatically maintain the inverse association for you. You can make it sensitive to changes on the owning side of the association, but that's as far as it goes.
As to why your test fails, cartDaoStub.findById(cartId) probably returns the same copy of the CartEntity that you already have loaded into the persistence context. Try calling entityManager.flush() followed by entityManager.clear() before making the assertion and the issue will probably go away.

How to fix "A different object with the same identifier value was already associated with the session" error when using one-to-one relationship

I'm trying to create a one-to-one relationship between 2 entities:
Project entity
#Entity
#Table(name = "projects")
public class Project {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToOne(mappedBy = "project", cascade = CascadeType.ALL, optional = false, fetch = FetchType.LAZY)
private CrawlerConfiguration crawlerConfiguration;
// Getters and setters ...
public void setCrawlerConfiguration(CrawlerConfiguration crawlerConfiguration) {
if (crawlerConfiguration == null) {
if (this.crawlerConfiguration != null) {
this.crawlerConfiguration.setProject(null);
}
} else {
crawlerConfiguration.setProject(this);
}
this.crawlerConfiguration = crawlerConfiguration;
}
CrawlerConfiguration entity
#Entity
#Table(name = "crawler_configurations")
public class CrawlerConfiguration {
#Id
private Long id;
#OneToOne(fetch = FetchType.LAZY)
#MapsId
private Project project;
// Getters and setters ...
}
When the user creates a new project, a configuration should also be created for the project.
#Transactional
public Project createProject(Project project) {
project.setCrawlerConfiguration(new CrawlerConfiguration());
return projectRepository.save(project);
}
Unfortunately it results in the following exception:
javax.persistence.EntityExistsException: A different object with the
same identifier value was already associated with the session :
[com.github.peterbencze.serritorcloud.model.entity.CrawlerConfiguration#1]
What is the correct way to create the entities?

Try this
#OneToOne(fetch = FetchType.LAZY)
#PrimaryKeyJoinColumn
private Project project;
In your CrawlerConfiguration entity

Hibernate "object references an unsaved transient instance"

My Users are in Organisations in a ManyToOne relationship, when a user is created with an existing Organisation I am trying to assign it to it without creating a new one.
In my service, here is how I create a user:
#Override
public UserInfo createUser(UserInfo newUser) {
// Check if organisation exists
OrganisationEntity orga = organisationDao.findByName(newUser.getOrganisation());
if (orga != null) {
// Organisation exists, we save it with the correct ID
return mapper.map(userDao.save(mapper.map(newUser, orga.getId())));
} else {
// Organisation does NOT exists, we save it and create a new one
return mapper.map(userDao.save(mapper.map(newUser, (long) -1)));
}
}
With my Mapper (helping me to convert a model to an entity) being:
public UserEntity map(UserInfo userInfo, Long orgaId) {
UserEntity user = new UserEntity();
user.setEmail(userInfo.getEmail());
user.setFirstName(userInfo.getFirstName());
user.setLastName(userInfo.getLastName());
user.setPassword(userInfo.getPassword());
OrganisationEntity orga = new OrganisationEntity();
orga.setName(userInfo.getOrganisation());
// We set the organisation's ID
if (orgaId != -1)
orga.setId(orgaId);
user.setOrganisation(orga);
return user;
}
And here is my UserDao:
#Transactional
public interface UserDao extends CrudRepository<UserEntity, Long> {
UserEntity save(UserEntity user);
}
And finally the relation in my UserEntity:
#ManyToOne(targetEntity = OrganisationEntity.class, cascade = CascadeType.ALL)
#JoinColumn(name = "orga_id")
private OrganisationEntity organisation;
Creating a user with a new Organisation work but when I input an existing one, I get the following:
detached entity passed to persist
From my understanding it is a bidirectional consistency problem, but the answers did not help me so far.
Finally here are my Entity classes:
#Entity
#Table(name = "\"user\"")
public class UserEntity {
#Id
#Column(name = "user_id")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#NotNull
private String email;
#NotNull
private String firstName;
#NotNull
private String lastName;
#NotNull
private String password;
#ManyToOne(targetEntity = OrganisationEntity.class, cascade = CascadeType.ALL)
#JoinColumn(name = "orga_id")
private OrganisationEntity organisation;
// Getters & Setters
}
and
#Entity
#Table(name = "organisation")
public class OrganisationEntity {
#Id
#Column(name = "orga_id", unique = true)
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#NotNull
#Column(unique = true)
private String name;
// Getters & Setters
}

I have solved my problem,
As you can see in the mapper above, I am creating a new instance of OrganisatonEntity no matter what, even if it already exists !
So a small change in my code solved it:
public UserEntity map(UserInfo userInfo, OrganisationEntity organisationEntity);
instead of
public UserEntity map(UserInfo userInfo, Long orgaId);
When the organisation already exists, I then assign it to my UserEntity like such:
user.setOrganisation(organisationEntity);
instead of instantiating a new object.
Problem solved !

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