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)
Related
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
Initial Situation:
I have these two entities, GroceriesList and Product.
GroceriesList:
A GroceriesList can have several products.
#Entity
#Table(name = "lists")
public class GroceriesList {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "list_id")
private Long listId;
#Column(name = "list_name")
private String listName;
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "product_id", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "list_id", referencedColumnName = "product_id")
)
private Set<Product> products;
}
Products:
A Product can be allocated to several GroceriesLists
#Entity
#Table(name = "products")
public class Product {
public enum Category {
Dairy,
Fruit,
Vegetable,
Meat,
Grains
}
// Product ID Column, GenerationType.Identity refers to auto incr in Postgres
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "product_id")
private Long productId;
#Column(name = "product_name")
private String productName;
#Column(name = "product_vendor")
private String productVendor;
#Enumerated(EnumType.STRING)
#Column(name = "product_category")
private Category productCategory;
#Column(name = "product_storedquantity")
private Integer productStoredQuantity;
#JsonIgnore
#ManyToMany(mappedBy = "products")
private List<GroceriesList> groceriesLists;
}
The entities and relationships are stored in three different tables in Postgres(One for Lists, one for products, and one mapping table for the relationships).
The mapping table:
Mapping Table "lists_products"
A sample Product:
Sample Product with Id=4
The problem: I'm trying to create new lists, and that works. However, as you can spot from the Mapping Table Image, Hibernate inserts the IDs into the wrong columns. The list_id in the mapping table is currently getting the product_id, and the product_id in the mapping table is getting the list_id.
I have tried to change the order of column names & references in the #JoinTable annotation in the GroceriesList Entity. However, that throws a mapping Error. I assume my error lies somewhere in that annotation. Interestingly, Hibernate uses the correct SQL-Query. What am I missing here?
After consulting fladdimir's solution, it gave me an idea and I solved my issue. The problem lied within the #JoinColumn annotation, where I thought the "name = ..." property refers to the column name in the database.
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "product_id", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "list_id", referencedColumnName = "product_id")
)
private Set<Product> products;
However, that property refers to the declared variable inside the Entity in Spring Boot, i.e. listId
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "list_id")
private Long listId;
So, the working implementation of the #JoinTable Annotation should look like the following, where "name = ..." uses that variable name:
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "lists_products",
joinColumns = #JoinColumn(name = "listId", referencedColumnName = "list_id"),
inverseJoinColumns = #JoinColumn(name = "productId", referencedColumnName = "product_id")
)
private Set<Product> products;
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;
I have 3 entities User, Order, Item with a mapping like this:
#Entity
public class Item {
#Id
#Access(AccessType.PROPERTY)
private long id; // item id predefined
//..getters and setters
}
#Entity
public class Client {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
//...getters and setters
}
#Entity
public class Order {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(nullable = false)
#Access(AccessType.PROPERTY)
private Long id;
#ManyToOne(optional = false, fetch = FetchType.LAZY, cascade = {
CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.DETACH
})// without removing
//#JoinColumn(name = "client_id") - works fine
#JoinTable(name = "client_cr_order_cr_item",
joinColumns = #JoinColumn(name = "order_id"),
inverseJoinColumns = #JoinColumn(name = "client_id"))
private Client client;
#NotEmpty
#OneToMany(fetch = FetchType.LAZY, cascade = {
CascadeType.PERSIST, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.DETACH
})// without removing
#JoinTable(name = "client_cr_order_cr_item",
joinColumns = #JoinColumn(name = "order_id"),
inverseJoinColumns = #JoinColumn(name = "item_id"))
private List<Item> items;
//...getters and setters
}
When I persist order it fails with error:
ERROR: null value in column "item_id" violates not-null constraint
it generate query like this:
insert into client_cr_order_cr_item (client_id, order_id) values ()
i.e. it do not fill out segment_id field by some reason I don't know. But I refer to client not thru 3th table but using FK #JoinColumn(name = "client_id") , then it generate correct query:
insert into order_cr_item (order_id, item_id) values ()
Please, could you explain this behavior? Why mapping of client affect items? Is there any hint to make hibernate persists items to 3th table?
I am trying to change the id of my database entities from a single long to a composite id consisting of two long's which are encapsulated in my ID.class shown below. What annotations would you use for ManyToOne and OneToMany relations? Did I made a mistake with my annotations, especially with #JoinColumns, #Embeddable and #EmbeddedId. My problem is that relations are stored with null;
My ID class consist of an autogenerated long (pid) and a manually set secondary long (sid). This is the ID for all my entity classes:
#Embeddable
public class ID implements Serializable {
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private long pid;
#Column(nullable=false)
private long sid;
}
My Entity-class (example) has a many-to-one relation to Office a one-to-one relation to Settings (both relations are uni-directional).
#Entity
#Table(name="user")
public class User {
#EmbeddedId
private ID id;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumns({
#JoinColumn(name = "office_pid", referencedColumnName = "pid", updatable=false, insertable=false),
#JoinColumn(name = "office_sid", referencedColumnName = "sid", updatable=false, insertable=false)
})
private Office office;
#OneToOne(cascade={CascadeType.PERSIST, CascadeType.REMOVE}, fetch=FetchType.LAZY)
#JoinColumns({
#JoinColumn(name = "setting_pid", referencedColumnName = "pid", updatable=false, insertable=false),
#JoinColumn(name = "setting_sid", referencedColumnName = "sid", updatable=false, insertable=false)
})
private Settings setting;
#OneToMany(mappedBy = "user", cascade=CascadeType.REMOVE, fetch=FetchType.LAZY)
private List<Account> accounts= new ArrayList<>();
}
Office class (Many-To-One example):
#Entity
#Table(name = "office")
public class Office {
#EmbeddedId
private ID id;
#Column(length = 128)
private String description;
}
Account class (One-To-Many example):
#Entity
#Table(name="account")
public class Account {
#EmbeddedId
private ID id;
#Column(length = 16)
private String description;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumns({
#JoinColumn(name = "user_pid", referencedColumnName = "pid"),
#JoinColumn(name = "user_sid", referencedColumnName = "sid")
})
private User user;
}
Thanks in advance for your help.
Sequencing shouldn't be used if you want a composite pk - use only the sequence generated field which is unique, or composite business fields that are unique.
Second issue is the joinColumn definitions in User. You have marked them as updatable=false, insertable=false which means the foreign keys cannot be changed through the mappings, and is why they are always null regardless of setting the relationship. Remove the updatable=false, insertable=false settings from each to have the fields set when you set the relationship.