lazy,OSiV

Spring Web MVC

자동으로 Bean으로 등록된다. DispatcherSerlvet ViewResolver(spring-boot-starter-thymeleaf를 추가하여 타임리프를 사용할 수 있도록한다.) ….

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
        <dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
		</dependency>

Spring DATA Jpa

DataSource (Hikari CP) PlatformTransactionManager EntityManager

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.47</version>
		</dependency>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<version>1.4.197</version>
			<scope>test</scope>
		</dependency>

Web & JPA 를 함께 사용하면

OSiV 패턴 적용된다. OSiV를 적용하고 싶지 않다면? spring.jpa.open-in-view=false JPA 관계와 관련 Annontation

lazy로딩을 하려면 트랜잭션안에서만 가능하다. ex> Employee e = employeeRepository.getEmployee(1L); Job job = e.getJob(); // lazy 로딩 : select * from job where id = ? @OneToOne : FetchType.EAGER @OneToMany : FetchType.LAZY @ManyToOne : FetchType.EAGER @ManyToMany : FetchType.LAZY

JPQL : SELECT e FROM Employee e

참고 : 1 + n 문제 : http://wonwoo.ml/index.php/post/975

fetch join @BatchSize(size = 5) @Fetch(FetchMode.SUBSELECT)