Spring Boot으로 웹 출시까지 #11. JPA로 조회방법(FetchType) 설정하기

서로 연관된 두 테이블간의 조회방법 설정

• EAGER

 

• LAZY

 

N + 1 문제 및 해결방법 알아보기

 

 

 

User Controller에서 Fetch Type을 알아보자.

 

User Controller

package com.example.myhome.model;


import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.Data;

import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;

@Entity
@Data
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String username;
    private String password;
    private Boolean enabled;

    @ManyToMany
    @JoinTable(
            name = "user_role",
            joinColumns = @JoinColumn(name = "user_id"),
            inverseJoinColumns = @JoinColumn(name = "role_id"))

    @JsonIgnore
    private List<Role> roles = new ArrayList<>();

//    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
    @OneToMany(mappedBy = "user", fetch = FetchType.LAZY)
    private List<Board> boards = new ArrayList<>();

}

 

 

 

postman에서 get으로 해주자.

localhost:8080/api/users/3

 

 

User Controller에서 @JsonIgnore을 넣어주어 권한이 없게 만들어 준다.

@JsonIgnore
@ManyToMany
@JoinTable(
        name = "user_role",
        joinColumns = @JoinColumn(name = "user_id"),
        inverseJoinColumns = @JoinColumn(name = "role_id"))
private List<Role> roles = new ArrayList<>();

 

그러면 아래와 같이 쿼리가 나오는데

 

 

Spring boot pretty sql을 검색해서 아래 코드를 넣어준다.

spring.jpa.properties.hibernate.format_sql=true

 

 

쿼리가 보기 좋게 나온다.

 

 

@JsonIgnore를 넣어서 필요없는 쿼리는 보이지 않게 해주자.

 

User Controller

//    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
    @OneToMany(mappedBy = "user", fetch = FetchType.LAZY)
    @JsonIgnore
    private List<Board> boards = new ArrayList<>();

 

 

 

UserApiController에서 findAll을 통해서 user 정보의 모든 쿼리를 다 볼 수 있다.

 

UserApiController에서 아래와 같이 변수를 받도록 해주자.

@GetMapping("/users")
List<User> all() {
    List<User> users = repository.findAll();
    return users;
}

 

그리고 User Class에서 fetchtype을 lazy로 바꿔준다.

//    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
    @OneToMany(mappedBy = "user", fetch = FetchType.LAZY)
    @JsonIgnore
    private List<Board> boards = new ArrayList<>();

 

 

 

첫번째 user의 Board를 호출해보자.

 

@RestController
@RequestMapping("/api")
@Slf4j
class UserApiController {

@GetMapping("/users")
List<User> all() {
    List<User> users = repository.findAll();
    users.get(0).getBoards().size();
    return users;
}

 

 

 

 

UserApiController 아래와 같이 설정

package com.example.myhome.controller;

import com.example.myhome.model.Board;
import com.example.myhome.model.User;
import com.example.myhome.repository.UserRepository;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api")
@Slf4j
class UserApiController {

    @Autowired
    private UserRepository repository;

    @GetMapping("/users")
    List<User> all() {
        List<User> users = repository.findAll();
        log.debug("getBoards().size() 호출전");
        log.debug("getBoards().size() : {}", users.get(0).getBoards().size());
        log.debug("getBoards().size() 호출후");
        users.get(0).getBoards().size();
        return users;
    }

    @PostMapping("/users")
    User newUser(@RequestBody User newUser) {
        return repository.save(newUser);
    }

    // Single item

    @GetMapping("/users/{id}")
    User one(@PathVariable Long id) {
        return repository.findById(id).orElse(null);
    }

    @PutMapping("/users/{id}")
    User replaceUser(@RequestBody User newUser, @PathVariable Long id) {

        return repository.findById(id)
                .map(user -> {
//                    user.setTitle(newuser.getTitle());
//                    user.setContent(newuser.getContent());
//                    user.setBoards(newUser.getBoards());
                    user.getBoards().clear();
                    user.getBoards().addAll(newUser.getBoards());
                    for(Board board : user.getBoards()) {
                        board.setUser(user);
                    }
                    return repository.save(user);
                })
                .orElseGet(() -> {
                    newUser.setId(id);
                    return repository.save(newUser);
                });
    }

    @DeleteMapping("/users/{id}")
    void deleteUser(@PathVariable Long id) {
        repository.deleteById(id);
    }
}

 

 

 

 

ApplicationProperties에서 아래 구문 추가

logging.level.com.example=DEBUG 

spring.datasource.url=jdbc:mariadb://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=1234
spring.datasource.driver-class-name=org.mariadb.jdbc.Driver
logging.level.org.hibernate.SQL=DEBUG
logging.level.com.example=DEBUG 
logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE
spring.jpa.properties.hibernate.format_sql=true

 

 

 

여기서 EntityGraph 참고

 

UserRepository를 아래와 같이 설정(User의 변수명 참고)

package com.example.myhome.repository;

import com.example.myhome.model.Board;
import com.example.myhome.model.User;
import org.springframework.data.jpa.repository.EntityGraph;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface UserRepository extends JpaRepository<User, Long> {
    @EntityGraph(attributePaths = { "boards" })
    List<User> findAll();


    User findByUsername(String username);
}

 

 

 User의 Boards 변수명

@JsonIgnore
private List<Board> boards = new ArrayList<>();

 

 

지금 아래 에러가 계속해서 떠서 확인이 불가하다. 해결하고 넘어가자.

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-06-04 18:09:10.378 ERROR 98911 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'webSecurityConfig': Requested bean is currently in creation: Is there an unresolvable circular reference?
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.beforeSingletonCreation(DefaultSingletonBeanRegistry.java:355) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:227) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:410) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.20.jar:5.3.20]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.resolveBeanReference(ConfigurationClassEnhancer.java:362) ~[spring-context-5.3.20.jar:5.3.20]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:334) ~[spring-context-5.3.20.jar:5.3.20]
	at com.example.myhome.config.WebSecurityConfig$$EnhancerBySpringCGLIB$$56c24912.passwordEncoder(<generated>) ~[classes/:na]
	at com.example.myhome.config.WebSecurityConfig.configureGlobal(WebSecurityConfig.java:43) ~[classes/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:724) ~[spring-beans-5.3.20.jar:5.3.20]

 

 

 

 

 

 

 

 

 

 

 

< 참고 :Spring Boot으로 웹 출시까지 #11. JPA로 조회방법(FetchType) 설정하기 >

https://www.youtube.com/watch?v=K3PU_rKtGLc&list=PLPtc9qD1979DG675XufGs0-gBeb2mrona&index=11