假设这两个简单的查询:
def findById(id: Long): Option[Account] = database.withSession { implicit s: Session =>
val query = for (a <- Accounts if a.id === id) yield a.*
query.list.headOption
}
def findByUID(uid: String): Option[Account] = database.withSession { implicit s: Session =>
val query = for (a <- Accounts if a.uid === uid) yield a.*
query.list.headOption
}
我想重写它以将样板重复删除为:
def findBy(criteria: ??? => Boolean): Option[Account] = database.withSession {
implicit s: Session =>
val query = for (a <- Accounts if criteria(a)) yield a.*
query.list.headOption
}
def findById(id: Long) = findBy(_.id === id)
def findByUID(uid: Long) = findBy(_.uid === uid)
我不知道如何实现它,因为有一些隐含的转换涉及到我尚未解开的for comprehension。更具体地说:??? => Boolean
方法中findBy
的类型是什么?
修改
这些是帐户和帐户类:
case class Account(id: Option[Long], uid: String, nick: String)
object Accounts extends Table[Account]("account") {
def id = column[Option[Long]]("id")
def uid = column[String]("uid")
def nick = column[String]("nick")
def * = id.? ~ uid ~ nick <> (Account, Account.unapply _)
}
答案 0 :(得分:4)
我有这个助手表:
abstract class MyTable[T](_schemaName: Option[String], _tableName: String) extends Table[T](_schemaName, _tableName) {
import scala.slick.lifted._
def equalBy[B: BaseTypeMapper]
(proj:this.type => Column[B]):B => Query[this.type,T] = { (str:B) =>
Query[this.type,T,this.type](this) where { x => proj(x) === str} }
}
现在你可以做到:
val q=someTable.equalBy(_.someColumn)
q(someValue)