MS Lesson12: n + 1 problem

 

package guru.springframework.cruddemo.entity;

import jakarta.persistence.CascadeType;
import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.OneToMany;
import jakarta.persistence.OneToOne;
import jakarta.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;

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

@Getter
@Setter
@Entity
@Builder
@ToString
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "persons")
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false, unique = true)
    private String email;

//    @OneToOne(mappedBy = "person", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
//    @OneToOne(mappedBy = "person", orphanRemoval = true)
//    private Address address;

    @Builder.Default
    @OneToMany(mappedBy = "person", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
    private List<Car> cars = new ArrayList<>();

}

package guru.springframework.cruddemo.entity;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.OneToOne;
import jakarta.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;

@Getter
@Setter
@Entity
@Builder
@ToString
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "addresses")
public class Address {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private String country;

    @Column(nullable = false)
    private String city;

//    @ToString.Exclude
//    @OneToOne(optional = false)
//    @JoinColumn(name = "person_id", nullable = false, unique = true)
//    private Person person;

}

package guru.springframework.cruddemo.entity;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.ManyToOne;
import jakarta.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;

@Getter
@Setter
@Entity
@Builder
@ToString
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "cars")
public class Car {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private String brand;

    @Column(nullable = false)
    private String model;

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

}

package guru.springframework.cruddemo;

import guru.springframework.cruddemo.entity.Person;
import guru.springframework.cruddemo.repository.PersonRepository;
import lombok.RequiredArgsConstructor;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.List;

@SpringBootApplication
@RequiredArgsConstructor
public class CrudDemoApplication implements CommandLineRunner {

    private final PersonRepository repository;

    public static void main(String[] args) {
        SpringApplication.run(CrudDemoApplication.class, args);
    }

    @Override
    public void run(String... args) {
        List<Person> all = repository.findAll();

    }

}