Question

我们说我有两张桌子：

people:

id: long | uuid: UUID     | name: String

----

cars

id: long | owner_id: long | name: String

其中owner是people.id的外键。

我有一个查询，按照所有者的uuid选择所有车主（仅限API设计）。

问题是：如何在一个必须通过其people.id（uuid）然后SELECT id from people where uuid = ?获取SELECT * from cars where owner_id = id的交易中执行以下查询？< / p>

当然，我最初可以从id的{{1}}表中获取people，例如

uuid

然后运行另一个查询以val ownerId = db run people.filter(_.uuid === uuid.bind).map(_.id).result.head选择汽车：

owner_id

但这不会发生在一次交易中。有什么想法吗？

Answer 1

光滑动作有一种transactionally方法。你应该使用：

import slick.driver.PostgresDriver.api._  // for example

val query = for {
  p <- peoples.filter(_.uuid === "some-id")
  c <- cars.filter(_.owner_id === p.uuid)
} yield (p, c)

val action = query.result
val transactionalAction = action.transactionally // will be executed 
                                                 // in single transaction

// Ungrouped result
// TODO: You can group on db side by your query or 
// on client side using groupBy from collection API
val result:Future[Seq[(People, Cars)]] = db.run(transactionalAction)

Answer 2

我说：

val groupByQuery =  cars.join(people)
 .on (_.owner_id === _.id)
 .map{
  case (car, owner) => (owner.uuid, car)
 }
.groupBy(_._1)

db.run(groupByQuery)

Slick：两个查询，一个事务

2 个答案: