Непонимание JPA FetchTypes ⇐ JAVA

[Anonymous]

У меня есть 4 объекта: Лицо, Контакт, Адрес и Курс
Ниже приведена диаграмма отношений: -

Ниже приведены мои фрагменты кода:-
Классы сущностей

Код: Выделить всё

package com.anshu.example.model;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.util.HashSet;
import java.util.Set;

@Setter
@Getter
@Entity
@Table(name = "person")
public class Person extends BaseEntity {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "person_id")
private Integer personId ;
private String name ;
private int age ;

@OneToOne(fetch = FetchType.EAGER , cascade = CascadeType.ALL , targetEntity = Contact.class)
@JoinColumn(name = "contact_id" , referencedColumnName = "contact_id" , nullable = false)
private Contact contact ;

@OneToMany(mappedBy = "person" , cascade = CascadeType.ALL , fetch = FetchType.LAZY , targetEntity = Address.class)
private Set addresses = new HashSet();

@ManyToMany(mappedBy = "persons" , cascade = CascadeType.ALL , fetch = FetchType.LAZY)
private Set courses = new HashSet() ;

}

Код: Выделить всё

package com.anshu.example.model;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.util.ArrayList;
import java.util.List;

@Setter
@Getter
@Entity
public class Course extends BaseEntity{

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "course_id")
private Long courseId ;

private String name ;

private float hours ;

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "course_person" , joinColumns = {
@JoinColumn(name = "course_id" , referencedColumnName = "course_id")
} , inverseJoinColumns = {
@JoinColumn(name = "person_id" , referencedColumnName = "person_id")
})
private List
 persons = new ArrayList() ;
}

Код: Выделить всё

package com.anshu.example.model;

import jakarta.persistence.*;
import jakarta.validation.constraints.Email;
import jakarta.validation.constraints.NotBlank;
import jakarta.validation.constraints.NotNull;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

@Setter
@Getter
@Entity
public class Contact extends BaseEntity {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "contact_id")
private Integer contactId ;

@Column
@NotNull
@NotBlank(message = "Name should not be blank")
private String name ;

@NotNull
@Email(message = "Email format is wrong")
@NotBlank
@Column
private String email ;

@NotBlank
@Column
private String message ;

@Enumerated(EnumType.STRING)
private Status status ;

private enum Status {
OPEN ,
CLOSED
}

}

Код: Выделить всё

package com.anshu.example.model;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

@Entity
@Table
@Setter
@Getter
public class Address extends BaseEntity {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer addressId ;

private String city ;

private String state ;

private String country  ;

@ManyToOne(optional = false , fetch = FetchType.LAZY)
@JoinColumn(name = "person_id"  , referencedColumnName = "person_id")
private Person person ;
}

Код: Выделить всё

package com.anshu.example.model;

import jakarta.persistence.Column;
import jakarta.persistence.EntityListeners;
import jakarta.persistence.MappedSuperclass;
import lombok.Data;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import org.springframework.data.annotation.CreatedBy;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedBy;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;

import java.time.LocalDateTime;

@Getter
@Setter
@MappedSuperclass
@EntityListeners(AuditingEntityListener.class)
public class BaseEntity {
@Column(name = "created_at" , updatable = false)
@CreatedDate
private LocalDateTime createdAt ;

@Column(name = "created_by" , updatable = false)
@CreatedBy
private String createdBy ;

@LastModifiedDate
@Column(name = "updated_at" )
private LocalDateTime updatedAt ;

@Column(name = "updated_by" )
@LastModifiedBy
private String updatedBy ;
}

Класс обслуживания

Код: Выделить всё

package com.anshu.example.service;

import com.anshu.example.model.Address;
import com.anshu.example.model.Course;
import com.anshu.example.model.Person;
import com.anshu.example.repo.PersonRepo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import java.util.Arrays;
import java.util.List;

@Slf4j
@Service
public class PersonService {

private final PersonRepo personRepo  ;

public PersonService(PersonRepo personRepo) {
this.personRepo = personRepo ;
}

public Person save(Person person) {
log.info(person.toString());
for(Address address : person.getAddresses()) {
address.setPerson(person);
}

for(Course course : person.getCourses()) {
course.setPersons(List.of(person));
}

Person savedPerson =  personRepo.save(person) ;
removeDepth(savedPerson);
return savedPerson ;
}

public List findAll() {
List personList =  personRepo.findAll() ;
//        for(Person person : personList) {
//            removeDepth(person);
//        }

return personList ;
}

private void removeDepth(Person savedPerson) {
for(Address address : savedPerson.getAddresses()) {
address.setPerson(null);
}

for(Course course : savedPerson.getCourses()) {
course.setPersons(null);
}
}
}

Вы можете видеть, что в личном классе я пытаюсь получить только контакты с нетерпением, других я пытаюсь получить лениво.
Теперь, когда я вызываю метод службы findAll(), я должен видеть только один запрос, запущенный в моей консоли. Запрос должен получать данные о человеке и иметь соединение с таблицей контактов . Я не должен видеть никаких запросов на получение курсов и адресов, поскольку я не пытался получить их, используя какой-либо метод получения или что-то еще. Но я вижу следующее. Я ожидаю чего-то неправильного?

Код: Выделить всё

Hibernate:
select
p1_0.person_id,
p1_0.age,
p1_0.contact_id,
p1_0.created_at,
p1_0.created_by,
p1_0.name,
p1_0.updated_at,
p1_0.updated_by
from
person p1_0
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
c1_0.contact_id,
c1_0.created_at,
c1_0.created_by,
c1_0.email,
c1_0.message,
c1_0.name,
c1_0.status,
c1_0.updated_at,
c1_0.updated_by
from
Contact c1_0
where
c1_0.contact_id=?
Hibernate:
select
a1_0.person_id,
a1_0.addressId,
a1_0.city,
a1_0.country,
a1_0.created_at,
a1_0.created_by,
a1_0.state,
a1_0.updated_at,
a1_0.updated_by
from
Address a1_0
where
a1_0.person_id=?
2025-01-13T03:45:15.860+05:30  WARN 6840 --- [example] [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Ignoring exception, response committed already: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Document nesting depth (1001) exceeds the maximum allowed (1000, from `StreamWriteConstraints.getMaxNestingDepth()`)
2025-01-13T03:45:15.860+05:30  WARN 6840 --- [example] [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Document nesting depth (1001) exceeds the maximum allowed (1000, from `StreamWriteConstraints.getMaxNestingDepth()`)]

Как это происходит и как это преодолеть?

Подробнее здесь: https://stackoverflow.com/questions/793 ... erstanding