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开源软件名称（OpenSource Name）：line/kotlin-jdsl开源软件地址(OpenSource Url)：https://github.com/line/kotlin-jdsl开源编程语言(OpenSource Language)：Kotlin 100.0%开源软件介绍(OpenSource Introduction)：Kotlin JDSL
Kotlin JDSL is DSL for JPA Criteria API without generated metamodel and reflection. It helps you write a JPA query like writing an SQL statement. BackgroundThere are several libraries in the easy way to use JPA. However, those libraries have to use APT. If you use APT, there is a problem that you have to compile again when the name or type of entity field is changed. So, in order not to use APT, we created this library using the KProperty created by the kotlin compiler. Quick startReactiveIf you are interested in JPA Reactive See more HibernateAdd Hibernate Kotlin JDSL and Hibernate to dependencies dependencies {
implementation("com.linecorp.kotlin-jdsl:hibernate-kotlin-jdsl:x.y.z")
implementation("org.hibernate:hibernate-core:x.y.z")
}EclipselinkAdd Eclipselink Kotlin JDSL and Eclipselink to dependencies dependencies {
implementation("com.linecorp.kotlin-jdsl:eclipselink-kotlin-jdsl:x.y.z")
implementation("org.eclipse.persistence:org.eclipse.persistence.jpa:x.y.z")
}Create QueryFactory using EntityManager val queryFactory: QueryFactory = QueryFactoryImpl(
criteriaQueryCreator = CriteriaQueryCreatorImpl(entityManager),
subqueryCreator = SubqueryCreatorImpl()
)Query using it queryFactory.listQuery<Entity> {
select(entity(Book::class))
from(entity(Book::class))
where(column(Book::id).equal(1000))
}Spring DataIf you use Spring Boot & Data Frameworks See more UsageYou can easily write query using Entity associations.
If you want to return the DTO, use the DTO as the return type.
QueryQueryFactory allows you to create JPA queries using DSL just like SQL queries. val books: List<Book> = queryFactory.listQuery {
select(entity(Book::class))
from(entity(Book::class))
where(column(Book::author).equal("Shakespeare"))
}DTO ProjectionsIf you want to select the DTO, select columns in the order of constructor parameters. selectdata class Row(
val author: String,
val count: Long,
)
val books: List<Row> = queryFactory.listQuery {
select(listOf(column(Book::author), count(column(Book::id))))
from(entity(Book::class))
groupBy(column(Book::author))
}selectMultidata class Row(
val author: String,
val count: Long,
)
val books: List<Row> = queryFactory.listQuery {
selectMulti(column(Book::author), count(column(Book::id)))
from(entity(Book::class))
groupBy(column(Book::author))
}Update & DeleteUsers can perform bulk update/delete through update/delete query.
val query: Query = queryFactory.updateQuery<Order> {
where(col(Order::purchaserId).`in`(1000, 2000))
setParams(col(Order::purchaserId) to 3000)
}
val updatedRowsCount: Int = query.executeUpdate()
val deleteQuery: Query = queryFactory.deleteQuery<Order> {
where(col(Order::purchaserId).`in`(1000, 2000))
}
val deletedRowsCount: Int = deleteQuery.executeUpdate()ExpressionKotlin JDSL supports various expressions. Aggregationval max = max(column(Book::price))
val count = count(column(Book::price))
val greatest = greatest(column(Book::createdAt))Case Whenval case = case(
`when`(column(Book::name).like("A%")).then(literal(1)),
`when`(column(Book::name).like("B%")).then(literal(2)),
// ...
`else` = literal(999)
)Subqueryval authorIds = queryFactory.subquery<Long> {
select(column(Book::authorId))
from(entity(Book::class))
// ...
}
val authors: List<Author> = queryFactory.listQuery {
// ...
where(column(Author::id).`in`(authorIds))
}PredicateKotlin JDSL supports various predicates. val condition = and(
column(Book::author).equal("Shakespeare"),
column(Book::price).lessThanOrEqualTo(100.toBigDecimal()),
column(Book::status).`in`(SALE, OUT_OF_STOCK),
column(Book::createdAt).between(Time.of("2001-01-01"), Time.of("2010-12-31")),
)Joinval books = queryFactory.listQuery<Book> {
select(entity(Book::class))
from(entity(Book::class))
join(Book::author) //Default is `JoinType.INNER`
join(Book::publisher, JoinType.LEFT)
join(Book::seller, JoinType.RIGHT)
// ...
}Fetchval books = queryFactory.listQuery<Book> {
select(entity(Book::class))
from(entity(Book::class))
fetch(Book::author)
// ...
}If join and fetch are used together for the same entity, only fetch is applied. val books = queryFactory.listQuery<Book> {
select(entity(Book::class))
from(entity(Book::class))
join(Book::author) // Join is ignored
fetch(Book::author) // Only fetch is applied
// ...
}Cross Joinval books = queryFactory.listQuery<Book> {
select(entity(Book::class))
from(entity(Book::class))
join(entity(Author::class), on(column(Book::authorId).equal(column(Author::id))))
// ...
}AliasThere may be models with the two associations of same type. In this case, separate the Entity using alias. val orders = queryFactory.listQuery<Order> {
select(entity(Order::class))
from(entity(Order::class))
join(entity(Order::class), entity(Address::class, alias = "shippingAddress", on(Order::shippingAddress)))
join(entity(Order::class), entity(Address::class, alias = "receiverAddress", on(Order::receiverAddress)))
// ...
}associateassociate behaves similarly to join, and operates exactly the same as join in select, and since Join cannot be used in update/delete, use associate to associate the relationship with other internally mapped objects (ex: @Embedded) You can build it and run the query. val query = queryFactory.selectQuery<String> {
select(col(Address::zipCode))
from(entity(OrderAddress::class))
associate(OrderAddress::class, Address::class, on(OrderAddress::address))
}
val updatedRowCount = queryFactory.updateQuery<OrderAddress> {
where(col(OrderAddress::id).equal(address1.id))
associate(OrderAddress::class, Address::class, on(OrderAddress::address))
set(col(Address::zipCode), "test")
set(col(Address::baseAddress), "base")
}.executeUpdate()
val deletedRowCount = queryFactory.deleteQuery<OrderAddress> {
where(col(OrderAddress::id).equal(address1.id))
associate(OrderAddress::class, Address::class, on(OrderAddress::address))
}.executeUpdate()Treat (Downcasting)There may be situations where you need to downcast when using an Entity of an inheritance structure. In that case, you can use the code like below. val employees = queryFactory.listQuery<Employee> {
selectDistinct(entity(Employee::class))
from(entity(Employee::class))
treat<Employee, PartTimeEmployee>()
where(
col(PartTimeEmployee::weeklySalary).lessThan(1000.toBigDecimal()),
)
}If you are downcasting from the root entity (Project Entity in this case) that contains an entity with inheritance structure, you can do it as follows. val projects = queryFactory.listQuery<Project> {
selectDistinct(entity(Project::class))
from(entity(Project::class))
treat<Employee, FullTimeEmployee>(col(Project::employees))
where(
col(FullTimeEmployee::annualSalary).greaterThan(100000.toBigDecimal())
)
}For Hibernate, the issue at issue is currently unresolved and an additional inner(left) join is added to make the result It may come out as a duplicate. So you should always apply distinct to select above like examples If you are using Hibernate and want to fetch downcasting entities, the query cannot be executed normally. That is, the example below will result in a runtime error because of this issue. val sub = queryFactory.subquery<Long> {
select(col(Project::id))
from(entity(Project::class))
treat<Employee, FullTimeEmployee>(col(Project::employees))
treat<Employee, PartTimeEmployee>(col(Project::employees))
where(
or(
col(FullTimeEmployee::annualSalary).greaterThan(100000.toBigDecimal()),
col(PartTimeEmployee::weeklySalary).greaterThan(1000.toBigDecimal()),
)
)
}
val projects = queryFactory.listQuery<Project> {
val project = Project::class.alias("dedupeProject")
selectDistinct(project)
from(project)
val supervisor = Employee::class.alias("super")
val partTimeSuper = PartTimeEmployee::class.alias("partSuper")
// If you are using Hibernate and want to fetch downcasting entities, the query cannot be executed normally. That is, the example below will result in a runtime error.
fetch(project, supervisor, on(Project::supervisor))
treat(ColumnSpec<PartTimeEmployee>(project, Project::supervisor.name), supervisor, partTimeSuper)
where(
and(
col(project, Project::id).`in`(sub),
col(partTimeSuper, PartTimeEmployee::weeklySalary).equal(900.toBigDecimal()),
)
)
}If you want to use downcasting entity in select clause, Eclipselink does not support that function. An example is as follows. val employees = queryFactory.listQuery<FullTimeEmployee> {
val project: EntitySpec<Project> = Project::class.alias("project")
val fullTimeEmployee = FullTimeEmployee::class.alias("fe")
val employee = Employee::class.alias("e")
selectDistinct(fullTimeEmployee)
from(project)
treat(ColumnSpec<FullTimeEmployee>(project, Project::employees.name), employee, fullTimeEmployee)
where(
ColumnSpec<BigDecimal>(fullTimeEmployee, FullTimeEmployee::annualSalary.name)
.greaterThan(100000.toBigDecimal())
)
}
The Entity structure corresponds to the following structure. @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@Entity
@Table(name = "employee")
@DiscriminatorColumn(name = "EMP_TYPE")
class Employee(
@Id
@GeneratedValue
val id: Long,
val name: String
) {
override fun equals(other: Any?) = Objects.equals(id, (other as? Employee)?.id)
override fun hashCode() = Objects.hashCode(id)
}
@Entity
@Table(name = "fulltime_employee")
@DiscriminatorValue("F")
class FullTimeEmployee(
val annualSalary: BigDecimal,
override val id: Long,
override val name: String
) : Employee(id, name) {
override fun equals(other: Any?) = Objects.equals(id, (other as? FullTimeEmployee)?.id)
override fun hashCode() = Objects.hashCode(id)
}
@Entity
@Table(name = "parttime_employee")
@DiscriminatorValue("P")
class PartTimeEmployee(
val weeklySalary: BigDecimal,
override val id: Long,
override val name: String
) : Employee(id, name) {
override fun equals(other: Any?) = Objects.equals(id, (other as? PartTimeEmployee)?.id)
override fun hashCode() = Objects.hashCode(id)
}
@Entity
@Table(name = "contract_employee")
@DiscriminatorValue("C")
class ContractEmployee(
val hourlyRate: BigDecimal,
override val id: Long,
override val name: String
) : Employee(id, name) {
override fun equals(other: Any?) = Objects.equals(id, (other as? ContractEmployee)?.id)
override fun hashCode() = Objects.hashCode(id)
}
@Entity
@Table(name = "project")
class Project(
@Id
@GeneratedValue
val id: Long = 0,
val name: String,
@OneToMany(cascade = [CascadeType.ALL])
val employees: List<Employee>,
@OneToOne(cascade = [CascadeType.ALL], optional = false, fetch = FetchType.LAZY)
val supervisor: Employee
) {
override fun equals(other: Any?) = Objects.equals(id, (other as? Project)?.id)
override fun hashCode() = Objects.hashCode(id)
}
How it worksKotlin's property reference provides KProperty interface. KProperty is created in java file at kotlin compile time. Since KProperty has the name of property, we can use it to write the expression of the Critical API. If you type the JPA query as below, queryFactory.listQuery<Book> {
select(entity(Book::class))
from(entity(Book::class))
where(column(Book::name).equal("Hamlet").and(column(Book::author).equal("Shakespeare")))
}Kotlin compiler creates PropertyReference. final class ClassKt$books$1 extends PropertyReference1Impl {
public static final KProperty1 INSTANCE = new ClassKt$books$1();
books$1() {
super(Book.class, "name", "getName()Ljava/lang/String;", 0);
}
@Nullable
public Object get(@Nullable Object receiver) {
return ((Book) receiver).getName();
}
}
final class ClassKt$books$2 extends PropertyReference1Impl {
public static final KProperty1 INSTANCE = new ClassKt$books$2();
ClassKt$books$2() {
super(Book.class, "author", "getAuthor()Ljava/lang/String;", 0);
}
@Nullable
public Object get(@Nullable Object receiver) {
return ((Book) receiver).getAuthor();
}
}SupportIf you have any questions, please make Issues. And PR is always welcome. |
