3 笔交易 [英] Slick 3 Transactions

问题描述

我对光滑的 3 文档描述交易的方式感到困惑.我有 2 条看起来像这样的代码:

I'm confused by the way the slick 3 documentation describes transactions. I have slick 2 code that looks like this:

def doSomething(???) = DB.withTransaction { implicit session => 
    userDao.doSomething(???)
    addressDao.doSomething(???)
    contactDao.doSomething(???)
}

如何在 slick 3 中跨事务?

How can i span a transaction in slick 3?

推荐答案

请查看这里的文档 http://slick.typesafe.com/doc/3.0.0/dbio.html#transactions-and-pinned-sessions

我们的想法是将一系列 IO 操作包装到一个 transactionally 中，如下例所示:

The idea is that you wrap a sequence of IO operations into a transactionally like shown in this example:

val a = (for {
   ns <- coffees.filter(_.name.startsWith("ESPRESSO")).map(_.name).result
   _ <- DBIO.seq(ns.map(n => coffees.filter(_.name === n).delete): _*)
} yield ()).transactionally

val f: Future[Unit] = db.run(a)

这种方式 Slick 仍然以被动方式处理所有操作，但它会在一个事务中按顺序运行所有操作.

This way Slick still process all the operations reactively, but it runs them all in one transaction sequentially.

所以你的例子看起来像这样:

So your example would look like this:

def doSomething(???) = (for {
  _ <- userDao.doSomething(???)
  _ <- addressDao.doSomething(???)
  _ <- contactDao.doSomething(???)
} yield()).transactionally

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