I have a user table and a city table and I have a connecting table users_cities (columns: id, user_id, city_id). A user can follow multiple cities.
From the client side i send an array of cityIds. Some might be new some might still be selected and some might have been deselected.
What is a best practice to update the users_cities table with the data? Should I just delete everything for that particular userId and insert the new array or ... ?~
Also, how does one delete and repsectively insert the data in bulk, for a many to many reference?!
#Getter
#Setter
#NoArgsConstructor
#ToString
#Accessors(chain = true)
#Entity
#Table(name = "users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(unique = true)
private String email;
private String password;
private Boolean isGuest;
#ManyToMany(fetch = FetchType.EAGER)
private Set<Role> roles;
#ManyToOne()
#JoinColumn(name = "country_following_id")
private Country countryFollowing;
#ManyToMany()
private Set<City> citiesFollowing;
#ManyToMany()
private Set<Offer> offersFollowing;
}
and
#Getter
#Setter
#NoArgsConstructor
#ToString
#Accessors(chain = true)
#Entity
#Table(name = "cities")
public class City {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#NonNull
private Long id;
private String countryCode;
private String name;
#Latitude
private Double latitude;
#Longitude
private Double longitude;
}
Should I just delete everything for that particular userId and insert the new array
Since the relation connecting users and cities does not have an identity of its own, that sounds reasonable
Also, how does one delete and repsectively insert the data in bulk, for a many to many reference?
Just clear the User.citiesFollowing collection and populate it anew (hint: since you have cityIds at the ready, you can use EntityManager.getReference() to load the cities)
Related
I am using Spring JPA
I have 3 entities
1- Event
2- Seat
3- Reservation
Event has one to many relation with Seat and Reservation
Reservation has a one to many relation with Seat
(Event will have the seats created after its creation and then it will be assigned to the particular event)
(When users make reservations, each reservation can have multiple seats for the particular event)
What I've done so far:
The Event class
#Entity
#Data
#NoArgsConstructor #AllArgsConstructor
public class Event {
#Id
#GeneratedValue(strategy = AUTO)
private Long id;
#OneToMany(mappedBy = "event", fetch = FetchType.LAZY)
private List<Seat> seats;
#OneToMany(mappedBy = "event", fetch = FetchType.LAZY)
private List<Reservation> reservations;
}
The Seat class
#Entity
#Data
#AllArgsConstructor
#NoArgsConstructor
public class Seat {
#Id
#GeneratedValue(strategy = AUTO)
private Long id;
private String seatCode;
#ManyToOne(fetch = FetchType.LAZY)
#JoinTable(name = "event_seats")
private Event event;
#ManyToOne
#JoinTable(name = "seat_reservation")
private Reservation reservation;
}
The Reservation class
#Entity
#Data
#AllArgsConstructor
#NoArgsConstructor
public class Reservation {
#Id
#GeneratedValue(strategy = AUTO)
private Long id;
#ManyToOne
private User user;
#ManyToOne(fetch = FetchType.LAZY)
#JoinTable(name = "event_reservations")
private Event event;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "reservation")
private Collection<Seat> seats;
}
**Is the tables and relations design correct?
When I create a reservation and add seats to it, the linking table (reservation_seats) doesn't get updated.
And how to write a query to determine which Event seats are booked and which are not?**
There is more than one way to do this using JPA depending of your knowledge.
Options Like Native Query, JPQL or JPA Criteria.
The native query would be like this:
With reservation:
SELECT * FROM seat s WHERE s.id IN (SELECT seat_id FROM seat_reservation)
With no reservation:
SELECT * FROM seat s WHERE s.id NOT IN (SELECT seat_id FROM seat_reservation)
There may be other ways to do this, but I think it's enough.
I have two entity
#Entity
#Table(name = "user")
#Data
#Builder
#EqualsAndHashCode(callSuper=false)
#ToString
#AllArgsConstructor
#NoArgsConstructor
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "name")
private String name;
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#PrimaryKeyJoinColumn
private UserLastLogin userLastLogin;
}
#Entity
#Table(name = "lastLogin")
#EqualsAndHashCode(onlyExplicitlyIncluded = true)
#ToString(onlyExplicitlyIncluded = true)
#Data
#Builder
#AllArgsConstructor
#NoArgsConstructor
public class UserLastLogin implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "name")
private String userName;
#Column(name = "date")
private LocalDateTime date;
#OneToOne
#MapsId
#JoinColumn(name = "name")
private User user;
}
I use spring boot with spring data and jpa, hibernate in latest version.
In documentation is that #OneToOne is default EAGER, but when i get eager fetch object, i get lazyInitializationException when i not use #Transactional in get method. I don't understant why...
public UserDto getUser(String userName) {
var user= userRepository.getById(userName);
d.getSystemUserLastLogin(); // this throw lazy initialization exception
return mapper.entityToDto(d);
}
When i'will mark this method #Transactioal, this work. But, not recommendend used transactions in get method. I need use EAGER fetch in this relationship.
When i view query hibernate, i have one select, but children object is not available.
Hibernate:
select
user0_.name as nazwa1_4_0_,
user2_.name as name1_23_2_,
user2_.data as data3_23_2_
from
user0_
left outer join
last_login user2_
on user0_.name=user2_.name
where
user0_.name=?
The problem was that despite the fetch eager, lazy was used. This was due to the use of the getById method from the repository, which retrieves only the object's references and snaps all the fields when lazy is retrieved. Changing to findById solves the problem as findById takes an object, not a reference.
I would recommend you to use secondary tables instead like this:
#Entity
#Table(name = "user")
#Data
#Builder
#EqualsAndHashCode(callSuper=false)
#ToString
#AllArgsConstructor
#NoArgsConstructor
#SecondaryTable(name = "lastLogin", pkJoinColumns = #PrimaryKeyJoinColumn(name = "name"))
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "name")
private String name;
#Column(table = "lastLogin", name = "date")
private LocalDateTime date;
}
Also see https://www.baeldung.com/jpa-mapping-single-entity-to-multiple-tables for more details.
I have a problem with the historization of objects in the database.
the expected behavior of the save JpaRepository method is : Insert in the two tables idt_h and abo_h
But the current behavior is Insert in the idt_h table and update in the abo_h table.
#Data
#Entity
#Table(name = "ABO_H")
#AllArgsConstructor
#NoArgsConstructor
public class AboOP {
#Id
#Column(name = "ABO_ID")
private String id;
#Column(name = "ABO_STATUT")
private String statut;
#Column(name = "ABO_DATE_STATUT")
private Instant date;
#Column(name = "ABO_CoDE")
private String code;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumns({
#JoinColumn(name = "IDC_ID", referencedColumnName = "IDC_ID"),
#JoinColumn(name = "DATE_HISTO", referencedColumnName = "DATE_HISTO")
})
private IdtOP idtOP;
}
#Data
#Entity
#Table(name = "IDT_H")
#AllArgsConstructor
#NoArgsConstructor
public class IdtOP {
#AttributeOverrides({
#AttributeOverride(name = "id",
column = #Column(name = "IDC_ID")),
#AttributeOverride(name = "dateHisto",
column = #Column(name = "DATE_HISTO"))
})
#EmbeddedId
private IdGenerique idtId = new IdGenerique();
//Other fields
}
#Data
#AllArgsConstructor
#NoArgsConstructor
#Embeddable
public class IdGenerique implements Serializable {
private String id;
private Instant dateHisto;
}
I think that the class IdGenerique which groups the id and dateHisto is not well invoked for the table abo_h ??
thanks in advance
When you use the save() method, entityManager checks if the entity is new or not. If yes, the entity will be saved, if not, it'll be merged
If you implement your Entity Class with the inteface Persistable, you can override the method isNew() and make it returns True. In that case the save() method will persist, and not merge, your entity.
I'm trying to connect an entity (User) to entities they create which will be Surveys.
I have two repositories, one UserRepository and one SurveyRepository. I can load Surveys according to which User has them and currently they are all mapped by the User_ID, which is a field on the Survey entity.
However, when I try to remove a Survey, this removes my User whenever I define CascadeType.ALL.
But when I don't use that, I get another error "Caused by: java.sql.SQLIntegrityConstraintViolationException:"
I'm gussing this is all related to the password encryption I'm using, but I am not even trying to delete the User entity, I'm just deleting the Survey, which holds a reference, or an ID to the Survey..
I've tried CascadeType.All on both sides, and I've tried not having any CascadeType at all as well.. If I have it on both sides, this deletes the user whenever I tell my surveyRepository.delete(currentSurvey);
And whenever I don't have it on both sides, I get the exception above..
User Entity:
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "user_id")
private Long id;
#NotEmpty
#Email
#Column(unique = true)
private String email;
private String password;
#NotBlank
private String username;
#NotBlank
private String firstName;
#NotBlank
private String lastName;
#NotBlank private String role;
#OneToMany(fetch = FetchType.EAGER)
private Set<Survey> surveys = new HashSet<>();
Survey Entity:
#Entity
#Table(name = "survey")
public class Survey {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "survey_id")
private Long id;
private String title, creator, description;
private LocalDate date = LocalDate.now();
#OneToMany(orphanRemoval = true, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "survey_id")
#OrderBy("position ASC")
private Set<Question> questions = new HashSet<>();
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "user_id")
private User user;
I'm just not sure how I can tell JPA/Hibernate not to touch the User whenever we delete the Survey.
It doesn't matter if I save the User with Survvey or not does it?
Basically I've tried a lot of options and I figure I'm not quite grasping the issue, and I suspect it's about the annotations on the User side, but I still feel as if I should be able to delete the child entity with no problem at all since I am not touching the parent entity?
This is because of EAGER fetch type in User class for surveys.
You delete survey but because it is existed on surveys set in user yet, it wouldn't be deleted actually.
You need to do like this:
// User class
#OneToMany(cascade=CascadeType.ALL, orphanRemoval=true, mappedBy="user")
private Set<Survey> surveys = new HashSet<>();
//Survey class
#ManyToOne
#JoinColumn(name = "user_id")
private User user;
I have SpringBoot 2.1.3 and Java 8 application. Building DB with JPA I have 3 table in one to one relationship. Suppose the tables is the follows:
#Entity
#Data //lombok
#Table(name = "users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
private Address address;
}
And then:
#Entity
#Data
#Table(name = "address")
public class Address {
#Id
#Column(name = "id")
private Long id;
#OneToOne
#MapsId
private User user;
}
That's works.. and it is the best way to do (this exactly example is taken from documentation).
If I start the application the DB is created and if I tried to add entities all works well. The model created follows:
Now I want to add a Country object to my address Entities (for example) and I modified the Entities as follows:
#Entity
#Data
#Table(name = "address")
public class Address {
#Id
#Column(name = "id")
private Long id;
#OneToOne
#MapsId
private User user;
#OneToOne
#MapsId
private Country country;
}
And Country Entities:
#Entity
#Data
#Table(name = "country")
public class Country {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#OneToOne(mappedBy = "country", cascade = CascadeType.ALL)
private Address address;
}
The application still starts, the DB is created and the model follows:
But if I try to save a User as follows:
User user = new User();
Address address = new Address();
Country country = new Country();
user.setAddress(address);
address.setUser(user);
address.setCountry(country);
country.setAddress(address);
userRepository.save(user);
I obtain the error:
java.sql.SQLException: Field 'country_id' doesn't have a default value
Anyway I solve the issue removing #MapsId and added #JoinColumn but I would like to understand what's wrong.
P.S.: I'm using MySQL 5.7 with InnoDB dialect (setting on application.properties)
Thanks all
It works only with one #MapsId annotation. Using two is causing that country id is not inserted:
insert into Country (id) values (?)
insert into Users (id) values (?)
insert into Address (user_id) values (?)