问题描述
我有(工作)以下代码:
I have the (working) following code:
val actions = (for {
_ <- slickUsers.insertOrUpdate(dbUser)
loginInfo <- loginInfoAction
_ <- slickUserLoginInfos += DBUserLoginInfo(dbUser.userID, loginInfo.id.get)
} yield ()).transactionally
loginInfoAction 是 DBIOAction.我想将 loginInfoActions 更改为 DBIOAction 的 Seq,然后对它们中的每一个执行相同的 DBUserLoginInfo 操作.
with loginInfoAction being a DBIOAction. I would like to change loginInfoActions to a Seq of DBIOAction and for each of them, execute the same DBUserLoginInfo action afterwards.
我愚蠢地尝试了这个:
val actions = (for {
_ <- slickUsers.insertOrUpdate(dbUser)
loginInfoAction <- loginInfoActions
loginInfo <- loginInfoAction
_ <- slickUserLoginInfos += DBUserLoginInfo(dbUser.userID, loginInfo.id.get)
} yield ()).transactionally
但它没有按预期工作(我希望 loginInfoAction 会遍历 DBIOAction 的 Seq).我是 Slick 的新手,所以如果我遗漏了任何内容,请随时向我指出文档!
But it does not work as expected (I would have though loginInfoAction would iterate over the Seq of DBIOAction). I am a newbie in Slick so do not hesitate to point me to the documentation if I missed anything !
推荐答案
DBIO.sequence
使用DBIO.sequence
将List[DBIO[_]]
转换为DBIO[List[_]]
并使用for-comprehension.
Use DBIO.sequence
to convert List[DBIO[_]]
to DBIO[List[_]]
and use for-comprehension.
DBIO.sequence
将 DBIO 的序列转换为 DBIO[Seq[_]]
.
DBIO.sequence
will convert the sequence of DBIO's into DBIO[Seq[_]]
.
例如假设我们有一个函数 getUser
For example let say we have a function getUser
def getUser(userId: Long): DBIO[User]
def getAllUsers(userIds: List[Long]): DB[List[User]] = {
DBIO.sequence(userIds.map(getUser))
}
DBIO.Sequence
将 List[DBIO[_]]
转换为 DBIO[List[_]]
现在你的代码变成了
val actions = (for {
_ <- slickUsers.insertOrUpdate(dbUser)
loginInfoActionList <- DBIO.sequence(loginInfoActions)
_ <- DBIO.sequence { loginInfoActionList.map { loginInfo =>
slickUserLoginInfos += DBUserLoginInfo(dbUser.userID, loginInfo.id.get) }
}
} yield ()).transactionally
这篇关于Slick:将动作与 DIOAction 的 Seq 组合的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!