i have two tables Person and PersonType and there is a relation "ManyToMany" between these tables. During loading my application i am getting all the PersonTypes, but when i create new Person, i have an exception
org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "person_type_person_type_name_key"
Detail: Key (person_type_name)=(TYPE1) already exists.
person_type_person_type_name_key is my table where i should store the relations between Person and PersonType. When i create a new Person i DO NOT want to insert into PersonType table because the person type already exists. What should i do, not to insert into DB ? I am using personService.save(person); which is trying to insert also in person_type table into DB.
#Table(name = "person")
public class Person {
#Id
#Column(name = "id")
#GeneratedValue(generator = "person_id_seq")
#SequenceGenerator(sequenceName = "person_id_seq", name = "person_id_seq", schema = "manager", allocationSize = 1, initialValue = 1)
private Integer id;
#Column(name = "name")
private String name;
#Column(name = "password")
private String password;
#ManyToMany(cascade = {CascadeType.ALL})
#JoinTable(
name = "person_person_types",
joinColumns = #JoinColumn(name = "person_fk"),
inverseJoinColumns = #JoinColumn(name = "person_type_fk"))
private List<PersonType> personTypes;
}
#Entity
#Table(name = "person_type")
public class PersonType {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(name = "person_type_name", unique=true)
private String personType;
#ManyToMany(mappedBy = "personTypes", cascade = {CascadeType.ALL})
private Set<Person> persons;
}```
Maybe the problem is with inserting the PersonType. Ensure that you put PersonType with the same ID and same name into the DB. Also change CascadeType.ALL to be CascadeType.MERGE
Related
Using Hibernate, I have created two entities - Employee and EmployeeDetails. Since EmployeeDetails cannot exist without a corresponding entry in Employee, I figured I don't need an extra ID for EmployeeDetails, but could instead use the ID of the Employee entity. Here is how I have implemented this idea:
Employee-Entity:
#Entity
#Table(name = "employees")
#Data
public class Employee {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "employee_id")
private Long id;
#Column(name = "first_name", nullable = false)
private String firstName;
#Column(name = "last_name", nullable = false)
private String lastName;
#OneToOne(cascade = CascadeType.ALL)
EmployeeDetails employeeDetails;
}
Employee-Details-Entity:
#Entity
#Table(name = "employee_details")
#Data
public class EmployeeDetails {
#Id
private Long id;
#Column(name = "address")
private String address;
#Column(name = "e_mail", nullable = false)
private String eMail;
#Column(name = "phone")
private String phone;
#MapsId
#OneToOne(mappedBy = "employeeDetails", cascade = CascadeType.ALL)
#JoinColumn(name = "employee_id")
private Employee employee;
}
By adding the #MapsId annotation to the employee-variable inside EmployeeDetails, I should be assigning the primary key of the Employee-entity to the Id-column of EmployeeDetails.
In a second step, I have written some data into both of my tables.
employee table in MySQL database:
employee_id first_name last_name employee_details_employee_id
1 John Smith null
2 Jennifer Adams null
The last column was somehow generated by Hibernate. I don't understand why. It appears to be some column for identification, but I don't need it.
employee_details table in MySQL database:
employee_id address e_mail phone
1 null john.smith#gmail.com null
2 null jennifer.adams#gmail.com null
I have only assigned an e-mail to the employees. Surprisingly, there is no employee-entry in this database table. I don't really need it anyways, but I was expecting it. So yeah, I think I am doing something terribly wrong and would really appreciate some help.
Change mappedBy side, here useful links
https://vladmihalcea.com/change-one-to-one-primary-key-column-jpa-hibernate/
https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate/
https://javabydeveloper.com/one-one-bidirectional-association/
#Entity
#Table(name = "employees")
#Data
public class Employee {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "employee_id")
private Long id;
#Column(name = "first_name", nullable = false)
private String firstName;
#Column(name = "last_name", nullable = false)
private String lastName;
#OneToOne(mappedBy = "employee", cascade = CascadeType.ALL)
EmployeeDetails employeeDetails;
}
Entity
#Table(name = "employee_details")
#Data
public class EmployeeDetails {
#Id
private Long id;
#Column(name = "address")
private String address;
#Column(name = "e_mail", nullable = false)
private String eMail;
#Column(name = "phone")
private String phone;
#MapsId
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "employee_id")
private Employee employee;
}
#MapId is not a popular solution in work with Hibernate.
Maybe in your case, #Embeddable will be a better option?
If I understand correctly, EmployeeDetails cannot exist without correlated Employee. So, EmployeeDetails could be a field in Employee as an embeddable field:
#Entity
#Table(name = "employees")
#Data
public class Employee {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "employee_id")
private Long id;
#Column(name = "first_name", nullable = false)
private String firstName;
#Column(name = "last_name", nullable = false)
private String lastName;
#Embedded
EmployeeDetails employeeDetails;
}
Then EmployeeDetails doesn't need ID and relation with the employee:
#Embeddable
public class EmployeeDetails {
#Column(name = "address")
private String address;
#Column(name = "e_mail", nullable = false)
private String eMail;
#Column(name = "phone")
private String phone;
}
As you can see, now in the database it's only one table employees, but in our hibernate model, we have two separated objects. Probably you don't need EmployeeDetails without Employee entity, so there is more efficient construction.
If you really need a separated table for EmployeeDetails with relation to Employee I recommend creating standard one-to-one mapping instead of #MapId construction.
I have 3 tables which are Person Login and Account.
Person and Login is OneToOne relation and Login has one FK which is connected Person's id column called PERSON_ID.
Person(one) and Account(many) is OneToMany relation and Account has one FK which is connected Person's id column called PERSON_ID as well .
what i want to do is when i delete one data from Account , nothing happen to Person and Login.
if i delete one data from Person which id=1, Login's PERSON_ID=1 data will be deleted , and all of the data PERSON_ID=1 from Account will be deleted as well.
if i delete one data from Login which PERSON_ID=1, Person 's id=1 data will be deleted , and all of the data PERSON_ID=1 from Account will be deleted as well.
how should i set the cascade ?
i've tried dozens of times and still can't find the logic in there, thanks!!
here's my code of all 3 tables without setting cascade:
`
#Entity
#Table(name = "PERSON")
public class Person {
#Id
#Column(name = "ID", nullable = false, unique = true)
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
#Column(name = "NAME")
private String name;
#Column(name = "SEX")
private String sex;
#OneToMany(mappedBy = "person",fetch = FetchType.LAZY)
private List<Account> account;
#OneToOne(mappedBy = "person")
private Login login;
#get..
#set..
}
`
#Entity
#Table(name = "ACCOUNT")
public class Account {
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
#Column(name = "ACCOUNT")
private String account;
#Column(name = "AMOUNT")
private String amount;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "PERSON_ID",referencedColumnName = "ID")
public Person person;
#get..
#set..
}
`
#Entity
#Table(name = "LOGIN")
public class Login {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID")
private long id;
#Column(name = "USERNAME")
private String userName;
#Column(name = "PASSWORD")
private String password;
#OneToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "PERSON_ID", referencedColumnName = "ID")
private Person person;
#get..
#set..
}
It's been a while, but if I'm not mistaken you need to use the cascade=REMOVE option on the OneToMany and OneToOne relationships. In the OneToOne I think you need to specify cascade=REMOVE on the side that does NOT own the relationship, that is, the side that also contains the "mappedBy" property.
Finally, I believe JPA will NOT automatically load lazy relationships and then cascade them. I'm thinking you may need to fetch the relationship before you delete the parent entity (otherwise JPA will not know what to delete).
I am trying to create a new User(entity1) - it has reference to a Group (entity2) via a link table Member (entity3)
A user has a Set of groups as a class variable.
When i create my user object i want to say this user will be a member of group n (there are pre defined users that are linked to by id (1,2,3,4,5,6...) each group has some associated data in the table.
Whenever I create my user object as follows;
User user = new User();
user.setActive(1);
user.setCrby("me");
user.setUsername("username");
user.setCrdate("2016-06-20 12:42:53.610");
user.setCrwsref("...");
user.setModby("...");
user.setModdate("2016-06-20 12:42:53.610");
user.setModswref("..");
user.setBackground("Y");
user.setPassword("password");
user.setFullName("me");
Group group = new Group();
group.setId(1);
Group group2 = new Group();
group2.setId(2);
Set<Group> sets = new HashSet<Group>();
sets.add(group);
sets.add(group2);
user.setGroups(sets);
userDao.addUser(user);
I keep getting errors telling me that certain columns cannot be null. What I actually want to happen here is not to be doing an insert in to the group table but associating a user to a line in the group table. Is there a particular way I can prevent the columns in the group table being modified? I think I need to modify the mappings between the link table - this is how much pojos link right now
User
#Entity
#Table(name = "user")
public class User
{
#Id
#GeneratedValue
#Column(name = "id")
private int id;
#Column(name = "username")
private String username;
#Column(name = "password")
private String password;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinTable(name = "zmember", joinColumns = {#JoinColumn(name = "username")}, inverseJoinColumns = {#JoinColumn(name = "id")})
private Set<Group> groups = new HashSet<Group>(0);
Member link table
#Entity
#Table(name = "member")
public class Member implements Serializable
{
#Id
#GeneratedValue
#Column(name = "id")
private int id;
#Id
#Column(name = "sgpid")
private int sgpid;
#Column(name = "username")
private String memberUsername;
Group
#Entity
#Table(name = "group")
public class Group
{
#Id
#GeneratedValue
#Column(name = "id")
private int id;
What is happening is there is no association to the link Member table so ideally should User have a set of member objects rather than a set of groups?
Thanks - this was quite hard to explain so sorry if it is hard to understand
This is a typical case for the #ManyToMany annotation. See for example:
https://dzone.com/tutorials/java/hibernate/hibernate-example/hibernate-mapping-many-to-many-using-annotations-1.html
The relationship from User to Group is essentially ManyToMany. You could model this is using the #ManyToMany annotation however one drawback with this approach is you cannot save additional information about the group in the join table such as 'date_joined'.
See: https://en.wikibooks.org/wiki/Java_Persistence/ManyToMany#ManyToMany
Using this approach you would not need the Join entity Member and the relationship on User would look like:
#ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinTable(name = "zmember", joinColumns = {#JoinColumn(name = "member_id", referencedColumnName = "id")}, inverseJoinColumns = {#JoinColumn(name = "group_id", referencedColumnName = "id")})
private Set<Group> groups = new HashSet<Group>(0);
The alternative to using #ManyToMany is to use a Join entity Member(ship) as you have done. This would allow you to save additional data about the relationship (by defining additional field mappings in the Join entity).
In this case the mappings would look like:
User:
public class User{
#OneToMany(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<Membership> memberships = new HashSet<Membership>(0);
//if required, you can 'hide' the join entity from client code by
//encapsulating add remove operations etc.
public void addToGroup(Group group){
Membership membershup = new Membership();
membership.setUser(this);
membership.setGroup(group);
memberships.add(membership);
)
public Set<Groupp> getGroups(){
//iterate memberships and build collection of groups
}
}
Membership:
public class Membership{
#Id
#GeneratedValue
#Column(name = "id")
private int id;
#ManyToOne
#JoinColumn(name = "user_id")
private Member member;
#ManyToOne
#JoinColumn(name = "group_id")
private Group group;
}
Group:
#Entity
#Table(name = "group")
public class Group
{
#Id
#GeneratedValue
#Column(name = "id")
private int id;
#OneToMany(mappedBy = "group", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<Membership> memberships = new HashSet<Membership>(0);
}
Why Hibernate tries to insert new record with existing id?
Category table before save (was filled manually with insert)
ID | NAME | IMAGE
1 | 'NAME'| 'IMAGE'
Save code
//Category{id=0, name='NAME', image='IMAGE', parent=null}
getCurrentSession().save(category);
Should be inserted with id 2.
Category Java code
#Entity
#Table(name = "CATEGORY",
indexes = {
#Index(name = "CATEGORY_NAME_INDEX",
columnList = "CATEGORY_NAME")})
public class Category implements NamedModel {
#Id
#Column(name = "CATEGORY_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#NotNull
#Size(min = 1, max = 256)
#Column(name = "CATEGORY_NAME", length = 256)
private String name;
#OneToOne(fetch = FetchType.EAGER)
#JoinTable(name = "CATEGORY_RELATIONS",
joinColumns = {
#JoinColumn(name = "CATEGORY_RELATIONS_CATEGORY_ID",
referencedColumnName = "CATEGORY_ID")},
inverseJoinColumns = {
#JoinColumn(name = "CATEGORY_RELATIONS_PARENT_ID",
referencedColumnName = "CATEGORY_ID")})
private Category parent;
#OneToMany(cascade = {CascadeType.REMOVE, CascadeType.PERSIST},
fetch = FetchType.LAZY, mappedBy = "parent")
private List<Category> children;
}
SOLUTION
//Category
#GeneratedValue(strategy = GenerationType.IDENTITY)
//CategoryRelations
#Entity
#IdClass(CategoryRelationsPrimaryKey.class)
public static class CategoryRelationsPrimaryKey implements Serializable {
private Long categoryId;
private Long parentId;
instead of long.
This is because you had deleted/added a record from database directly instead from the application i.e. ORM, that's why values in hibernate_sequence is no longer maintained.
Hibernate maintains values in a hibernate_sequence table which would be inserted on creating a new record.
update next_val column value in hibernate_sequence to resolve the problem.
You can use Annotation #GeneratedValue(strategy = GenerationType.IDENTITY) to delegate primary key generation to database.
How fix next error?
ERROR SchemaExport:484 - HHH000389: Unsuccessful: alter table CATEGORY_RELATIONS add constraint FK2bn4xlg661b5xbx2qnwi1aqv0 foreign key (CATEGORY_RELATIONS_PARENT_ID) references CATEGORY
ERROR SchemaExport:485 - incompatible data types in combination in statement [alter table CATEGORY_RELATIONS add constraint FK2bn4xlg661b5xbx2qnwi1aqv0 foreign key (CATEGORY_RELATIONS_PARENT_ID) references CATEGORY]
hibernate.version 5.0.7.Final
hsqldb.version 2.3.3
Property, used for session factory
hibernate.dialect=org.hibernate.dialect.HSQLDialect
Category
#Entity
#Table(name = "CATEGORY",
indexes = {
#Index(name = "CATEGORY_NAME_INDEX",
columnList = "CATEGORY_NAME")})
public class Category extends JsonNamedModel {
#Id
#Column(name = "CATEGORY_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name = "CATEGORY_NAME")
private String name;
#Column(name = "CATEGORY_IMAGE")
private String image;
#OneToOne(cascade = CascadeType.REMOVE, fetch = FetchType.LAZY)
#JoinTable(name = "CATEGORY_RELATIONS",
joinColumns = {
#JoinColumn(name = "CATEGORY_RELATIONS_CATEGORY_ID", referencedColumnName = "CATEGORY_ID")},
inverseJoinColumns = {
#JoinColumn(name = "CATEGORY_RELATIONS_PARENT_ID", referencedColumnName = "CATEGORY_ID")})
private Category parent;
#OneToMany(cascade = CascadeType.REMOVE, fetch = FetchType.EAGER, mappedBy = "parent")
private List<Category> children;//...
}
CategoryRelations
#Entity
#Table(name = "CATEGORY_RELATIONS")
#IdClass(CategoryRelations.CategoryRelationsPrimaryKey.class)
public class CategoryRelations implements Serializable {
#Id
#Column(name = "CATEGORY_RELATIONS_CATEGORY_ID")
private String categoryId;
#Id
#Column(name = "CATEGORY_RELATIONS_PARENT_ID")
private String parentId;
#Entity
#IdClass(CategoryRelationsPrimaryKey.class)
public static class CategoryRelationsPrimaryKey implements Serializable {
private long categoryId;
private long parentId;
}//...
}
I think it's complaining because your types don't match up. In CATEGORY_RELATIONS you have the key types as String but in CATEGORY you have the primary key as an int. While in actual practice you might only store integer data in both fields, the DB engine can't prove that. There's nothing stopping somebody from putting a non-integer in CATEGORY_RELATIONS.categoryId and making it so the FK could never be satisfied.
Try changing CATEGORY_RELATIONS.categoryId to an int.
And now that I look at it, your PK class shows them as longs. Try switching all of the types in your CategoryRelations object (and possibly the CATEGORY_RELATIONS table) to all be the same types.