我需要能够通过在某些情况下提供除 User 之外的所有值来创建 id 对象，以便 User 对象负责为自己分配一个自动生成的值。
为此，我重载了伴生对象中的 apply 方法，如下所示。但这会导致编译时错误: value tupled is not a member of object 。
StackOverflow 和其他博客上提到的解决方案不起作用，例如:
http://queirozf.com/entries/slick-error-message-value-tupled-is-not-a-member-of-object
case class User(id: Long, firstName: String, lastName: String, mobile: Long, email: String)
object User {
private val seq = new AtomicLong
def apply(firstName: String, lastName: String, mobile: Long, email: String): User = {
User(seq.incrementAndGet(), firstName, lastName, mobile, email)
}
}
class UserTableDef(tag: Tag) extends Table[User](tag, "user") {
def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
def firstName = column[String]("first_name")
def lastName = column[String]("last_name")
def mobile = column[Long]("mobile")
def email = column[String]("email")
override def * =
(id, firstName, lastName, mobile, email) <> (User.tupled, User.unapply)
}
最佳答案
你的问题的根源是重载的 apply def。tupled 不适用于带有 case class 或 less than 2 parameters 的 overloaded apply 。
就 slick 的 *(或全部)映射和 <> 而言，它应该是这样的，
def * = (tupleMember1, tupleMember2, ...) <> (func1, func2)
这样，
func1 将该元组 (tupleMember1, tupleMember2, ...) 作为输入并返回映射类/案例类的实例。 func1 获取映射类/案例类的实例并返回该元组 (tupleMember1, tupleMember2, ...) 。 所以你可以提供任何功能......满足这些要求。
case class User(id: Long, firstName: String, lastName: String, mobile: Long, email: String)
object User {
private val seq = new AtomicLong
def apply(firstName: String, lastName: String, mobile: Long, email: String): User = {
User(seq.incrementAndGet(), firstName, lastName, mobile, email)
}
def mapperTo(
id: Long, firstName: String,
lastName: String, mobile: Long, email: String
) = apply(id, firstName, lastName, mobile, email)
}
class UserTableDef(tag: Tag) extends Table[User](tag, "user") {
def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
def firstName = column[String]("first_name")
def lastName = column[String]("last_name")
def mobile = column[Long]("mobile")
def email = column[String]("email")
override def * =
(id, firstName, lastName, mobile, email) <> ((User.mapperTo _).tupled, User.unapply)
}
关于scala - `apply` 方法重载时 : Slick error message 'value tupled is not a member of object' ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41179532/