JPA #JoinTable with composite (2 column) primary keys - java

In a spring-boot app, I've got the following entity definition:
#Data
#Entity
#Table(name = "users")
public class User {
#Id
#Column(nullable = false, name = "username", length = 100)
private String username;
#JoinTable(name = "userrole",
joinColumns = { #JoinColumn(name = "username") },
inverseJoinColumns = { #JoinColumn(name = "role") }
)
#OneToMany(
cascade = CascadeType.ALL,
orphanRemoval = true
)
private List<Role> roles;`
I'm using Spring-data-jpa,Hibernate with H2 as the database.
The trouble is that spring-data-jpa, hibernate always generate/creates the join table (DDL) 'userrole' with a single column primary key. e.g. 'username'.
Hence, if records such as {'username', 'user_role'} and {'username', 'admin_role'} is inserted in the join table ('userrole'), the next insert fails with an error due to the 'duplicate' primary key.
I've tried using both columns in the above definition, as well as the following variation:
#OneToMany(
cascade = CascadeType.ALL,
orphanRemoval = true
)
#JoinColumns({
#JoinColumn(name = "username"),
#JoinColumn(name = "role") })
private List<Role> roles;`
But that they resulted in the same or worse problems, e.g. and in the latter, even table creation fails because only a single column is used as primary key for the jointable. Role is simply another table with 2 columns 'role' and 'description', basically a role catalog.
How do we specify to JPA that the #JoinTable should use both 'username' and 'role' columns as composite primary keys?
edit:
I tried using an independent table/entity as suggested, thanks #Kamil Bęben
#Data
#Entity
#Table(name = "users")
public class User {
#Id
#Column(nullable = false, name = "username", length = 100)
private String username;
#OneToMany(
fetch = FetchType.EAGER,
cascade = CascadeType.ALL,
mappedBy = "username",
orphanRemoval = true
)
#ElementCollection
private List<UserRole> roles;
UserRole is defined as such
#Data
#NoArgsConstructor
#Entity
#Table(name = "userrole")
public class UserRole {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "userrole_seq")
Long id;
#Column(nullable = false, name = "username", length = 100)
private String username;
#Column(nullable = false, name = "role", length = 50)
private String role;
the repository for that user-roles join table is defined as
#Repository
public interface UserRoleRepository extends CrudRepository<UserRole, Long> {
UserRole findByUsernameAndRole(String username, String role);
List<UserRole> findByUsername(String username);
List<UserRole> findByRole(String role);
}
Admittedly, ugly, but that it works. And that somehow, it seemed to use the correct findByUsername() method to retrieve the roles as is relevant to the user, probably related to the 'mappedBy' clause. 'black magic'! There's lots more that I'd still need to find my way around JPA, Spring, Spring-data
edit2:
further update:
the original #JoinTable works as well.
But that the relations need to be specified as #ManyToMany
#ManyToMany(
fetch = FetchType.EAGER,
cascade = CascadeType.MERGE
)
#JoinTable(name = "usersroles",
joinColumns = { #JoinColumn(name = "username") },
inverseJoinColumns = { #JoinColumn(name = "role") }
)
private List<Role> roles = new ArrayList<Role>();
This creates 2 column primary keys as expected for the 'users-roles' table
Thanks to #Roman

If Role only has two columns, eg user_id and role, the way to map this in jpa would be as following
#ElementCollection
#CollectionTable(name = "user_roles", joinColumns = #JoinColumn(name = "user_id"))
#Column(name = "role")
List<String> roles = new ArrayList<>();
Otherwise, jpa really requires each entity's identifier and join columns to be separate columns, so Role entity would have to have columns like id, user_id and role_name. Could look like this .:
class Role {
#Id
Long id;
#ManyToOne
#JoinColumn(name = "user_id", referencedColumnName = "id");
User user;
String roleName;
// Other fields
}
And in the User entity
#OneToMany(mappedBy = "user") // user is Field's name, not a column
List<Role> roles = new ArrayList<>();
Further reading

Related

Many to many jpa relationship creating duplicated data in entity with new IDs

I have two jpa entities User + profile with many to many relationship like below :
User Entity
#Data
#Entity
#AllArgsConstructor
#NoArgsConstructor
#Table(name = "t_user")
public class UserEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "user_id")
private Long Id;
#Column(nullable = false)
private String username;
#Column(nullable = false, length = 14)
private String siret;
#Cascade({
org.hibernate.annotations.CascadeType.SAVE_UPDATE,
org.hibernate.annotations.CascadeType.MERGE,
org.hibernate.annotations.CascadeType.PERSIST
})
#ManyToMany(fetch = FetchType.LAZY,cascade = CascadeType.MERGE)
#JoinTable(name = "t_user_profile", joinColumns = {#JoinColumn(name = "user_id")},
inverseJoinColumns = {#JoinColumn(name = "profile_id")})
private Set<ProfileEntity> profiles = new HashSet<>();
#OneToOne(fetch = FetchType.LAZY,cascade = CascadeType.ALL)
#JoinColumn(name = "ressource_id")
private RessourceEntity ressource;
}
and Profile entity :
#Data
#Entity
#AllArgsConstructor
#NoArgsConstructor
#Table(name = "t_profile")
public class ProfileEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "profile_id")
private Long Id;
#Column(nullable = false)
#Enumerated(EnumType.STRING)
private Profiles profile;
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "profiles")
private Set<UserEntity> user = new HashSet<>();
}
The problem is when I send an http request contaning the same profiles with different users, I obtain new duplicated profiles records with new IDs in the Profile table in the database like below :
but the correct way is to add the informations ONLY in the joined table t_user_profile because profile already exists in profile table .
I tried cascade.All , persist and merge .... but the same result .
And if I remove cascade and i search for profile Id using findById and get the Id and insert... I got a problem when the profile is new and don't exist in DB and the problem is because I removed cascade ... So I want if the profile already exists , I want to add the relationship in the joined table ONLY.

Remove the first entity and its relationship without removing the second entity - Spring Data JPA

I have two entities, one of UserEntity and the other RoleEntity, the user can have multiple roles and the role can be used by multiple users, my entities look like:
#Entity
public class UsersEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(nullable = false)
private Long id;
//...
#ManyToMany(mappedBy = "users")
private Set<RolesEntity> roles;
//...
// Getters and setters
}
#Entity
public class RolesEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(nullable = false)
private Integer id;
#NotNull
#Enumerated(EnumType.STRING)
#Column(length = 20)
private RoleEnum name;
#JoinTable(name = "user_roles", joinColumns = {
#JoinColumn(name = "role_id", referencedColumnName = "id", nullable = false)}, inverseJoinColumns = {
#JoinColumn(name = "user_id", referencedColumnName = "id", nullable = false)})
#ManyToMany
private List<UsersEntity> users;
}
Generally roles are fixed they don't change a lot. Now I have a service:
public void removeUser(Long id) {
if (userRepository.findById(id).isPresent()) {
userRepository.deleteById(id);
} else {
throw new IllegalArgumentException("User not found!");
}
}
My requirement is to remove only the user and not the roles related with this user, which mean remove the user and the relation ship. When I call the previews method I got.
org.postgresql.util.PSQLException: ERROR: update or delete on table "users" violates foreign key constraint "constraint_user_id" on table "user_roles"
Detail: Key (id)=(4) is still referenced from table "user_roles".
Is there any trick to solve this please?
You need to make any references to that UsersEntity to be null.
So basically what is the problem? While RolesEntity has a reference to that UsersEntity class you cannot delete that. The most trivial thing to do is to make a loop for each RolesEntity in your UsersEntity class and remove everything from it.
Then you can successfully delete that user from your db.
Check this out to get more info: How to remove entity with ManyToMany relationship in JPA (and corresponding join table rows)?
I solved my issue like this, I'm not sure if this is a best approach to solve this:
public void removeUser(Long id) {
Optional<UsersEntity> userById = usersRepository.findById(id);
if (userById.isPresent()) {
UsersEntity user = userById.get();
for (RolesEntity role : user.getRoles()) {
role.setUsers(null);
rolesRepository.save(role);
}
usersRepository.delete(user);
} else {
throw new IllegalArgumentException("User not found!");
}
}
I think you can do this by using CascadeType.REMOVE
#ManyToMany(cascade = CascadeType.REMOVE, fetch = FetchType.EAGER)
#JoinTable(
name = "users_roles",
joinColumns = #JoinColumn(name = "user_id"),
inverseJoinColumns = #JoinColumn(name = "role_id"))
private List<Role> roles;

How I can Join this 3 Tables with JPA

I want to join these 3 Tables.
Here you see my Person Entity
#Entity
#Table(name = "Person", schema = "public")
public class PatientEntity {
#Id
#Column(name = "id")
private Long id;
#Column(name = "lastname")
private String name;
#OneToMany
#JoinTable(name = "person_contact", joinColumns = { #JoinColumn(name = "person_id") }, inverseJoinColumns = { #JoinColumn(referencedColumnName = "id") })
#Column(name = "contact")
private Set<ContactEntity> contacts;
//Getter Setters
And here is my contact entity:
#Entity
#Table(name="contact",schema="public")
public class ContactEntity {
#Id
#Column(name="id")
private Long id;
#Column(name="phone")
private String phone;
//Getter Setters
I just read the Persons from the Table with findById with a Spring JPARepository, but there is no Contact mapped. There is no error during my HTTP request, but instead of a Contact there is null and this error message:
com.sun.jdi.InvocationException occurred invoking method.
The business case is, that every Person can have one or more contact. Is it possible to make it with JPA Annotations or do I need to map it by myself with a JPQL? Or should I create an Entity for the middle table? (person_contact)
The Database is a PostgreSQL Database.
There is this notification too in the Log:
ERROR: column contacts0_.contacts_id does not exist
Perhaps you meant to reference the column "contacts0_.contact_id".
Position: 306
Your #JoinTable has incorrect #JoinColumn specifications and corresponds to the following ddl.
create table person_contact (person_id bigint not null, contacts_id bigint not null, primary key (person_id, contacts_id))
To map your db structure, use following (note removed #Column annotation)
#OneToMany
#JoinTable(name = "person_contact", joinColumns =
{
#JoinColumn(name = "person_id", referencedColumnName = "id"),
},
inverseJoinColumns = {
#JoinColumn(name = "contact_id", referencedColumnName = "id")
})
private Set<ContactEntity> contacts;
I also encourage you to read https://vladmihalcea.com/the-best-way-to-map-a-onetomany-association-with-jpa-and-hibernate/ and reconsider a db structure without a join table (depending on your load and the effort to make this db change)

Jpa: delete dependents instead of updating them

In my application every customer can have several accounts. I have the following data structure (a lot omitted for brevity):
#Entity
#Table(name = "CUSTOMER")
public class Customer {
#Id
#Column(length = 36, name = "CUSTOMER_ID", nullable = false, unique = true)
private String id;
#OneToMany
#JoinColumn(name = "OWNER_ID", referencedColumnName = "CUSTOMER_ID")
private List<Account> accounts;
}
#Entity
#Table(name = "ACCOUNT")
public class Account {
#Id
#Column(length = 36, name = "ACCOUNT_ID", nullable = false, unique = true)
private String id;
#Column(name = "OWNER_ID", nullable = false)
private String ownerId;
}
If I use JPA to delete a Customer, such as
entityManager.remove(customer);
it tries to update the related ACCOUNT.OWNER_ID fields with null. OWNER_ID is not nullable, so it throws a JDBCException and rolls back the transaction.
What I need to achieve is that the related ACCOUNT rows get deleted (if any). How can I do that?
Thank you
Update: I tried it with
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
but it does not change the behavior: still tries to update with null.
I think you need to be using cascading in order to remove the child elements. Try this:
#OneToMany(cascade = CascadeType.ALL)
#JoinColumn(name = "OWNER_ID", referencedColumnName = "CUSTOMER_ID")
private List<Account> accounts;
You should also reference the Customer in your account by a ManyToOne relationship and not the String id. I think this should solve your issue:
#Column(name = "OWNER_ID", nullable = false)
#ManyToOne
private Customer owner;

Hibernate, JPA cant delete one-to-many relation

I have one-to-many relation:
#Entity
#Table(name = "Users")
public class User {
#Id
#Column(name = "user_id", nullable = false)
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
#Column(name = "login", nullable = false)
private String login;
#Column(name = "password", nullable = false)
private String password;
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "role_id", nullable = false)
private Role role;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "user", cascade = javax.persistence.CascadeType.ALL)
private Set<Contacts> contacts = new HashSet<Contacts>();
And I'm trying to delete User object with all Contacts; I tried to use:
cascade = javax.persistence.CascadeType.ALL
cascade =
javax.persistence.CascadeType.REMOVE
#Cascade(CascadeType.DELETE) from org.hibernate.annotations
#Cascade(CascadeType.DELETE_ORPHAN) from org.hibernate.annotations
but nothing helped. I always get exception:
org.hibernate.util.JDBCExceptionReporter - Cannot delete or update a
parent row: a foreign key constraint fails
(contactmanager.contact, CONSTRAINT contact_ibfk_1 FOREIGN KEY
(user_id) REFERENCES
UPD
Code that deletes a User is as follows:
#Transactional
public void removeUser(User user) {
sessionFactory.getCurrentSession().delete(user);
}
I'll appreciate any help! Thanks.
My recommendation here would be to do the relationship management yourself. Cascading removes can be tricky (especially in a situation like yours where the owner of your bi-directional relationship is not the one declaring the cascade) and often times quite dangerous so I usually prefer to avoid them. Especially if you are running a version of JPA pre-2.0 then you don't have too much of a choice. I would just change the removal method to something like:
#Transactional
public void removeUser(User user) {
Set<Contacts> contacts = user.getContacts();
for (Contact contact : contacts) {
sessionFactory.getCurrentSession().delete(contact);
}
contacts.clear();
sessionFactory.getCurrentSession().delete(user);
}

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