[Note] Spring Data JPA 笔记

Author included in Spring

2023-01-23 209 words One minute

Contents

引入依赖

简单查询

预生成方法

自定义简单查询

属性查询

组合查询

自定义SQL查询

HQL

SQL

修改和删除

@Modifying
@Transactional

CANCEL 已命名查询

定义命名查询

调用命名查询

运行验证

复杂查询

分页查询

pageable

排序和限制

动态条件查询

@Test
fun testSpecification() {
    userRepository.deleteAll()

    val users = listOf<User>(
	User(null, "hello", 1),
	User(null, "world", 2),
	User(null, "holy", 3),
	User(null, "shit", 4)
    )

    userRepository.saveAll(users)

    val matchUsers = userRepository.findAll { root, query, criteriaBuilder ->
	  val p1 = criteriaBuilder.like(root.get("name"), "w%")
	  val p2 = criteriaBuilder.greaterThan(root.get("age"), 0)
	  criteriaBuilder.and(p1, p2)
    }

    matchUsers.forEach { println(it.name) }
}

实体关系映射

关系映射注解

实体类注解

@JoinColumn
@JoinTable

关系映射注解

@OneToOne
@OneToMany mappedBy = “variable-name”
@ManyToOne
@ManyToMany

如何构造映射类型，猜想: 先默认，再lazy?

一对一

一对多和多对一

多对多

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(
    name = "StudentRole",
    joinColumns = [JoinColumn(name = "userid", referencedColumnName = "id")],
    inverseJoinColumns = [JoinColumn(name = "roleid", referencedColumnName = "id")]
)
val roles: List<Role>

@JoinTable 中间表的描述

@Entity(name = "Permissions")
class Permission(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    val id: Long?,
    @Column(nullable = false)
    val name: String,
    @Column(nullable = false)
    val type: String,
    @Column(nullable = false)
    val url: String,
    @Column(nullable = false)
    val code: String,

    @ManyToMany(mappedBy = "permission", fetch = FetchType.LAZY)
    val roles: Set<Role>
)

@Entity(name = "Roles")
class Role(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    val id: Long?,
    @Column(nullable = false)
    val name: String,
    @OneToMany(mappedBy = "role", fetch = FetchType.LAZY, cascade = [CascadeType.ALL])
    val users: Set<User>,

    @ManyToMany(cascade = [CascadeType.MERGE], fetch = FetchType.LAZY)
    @JoinTable(name = "Role_Permission")
    val permissions: Set<Permission>
)