Scala Slick 3.0中的继承实现

拥有case类+光滑表映射

很多类使用相同的字段，比如

class T1(tag: Tag) extends Table[caseClassA](tag, "A") {
  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}


class T2(tag: Tag) extends Table[caseClassB](tag, "B") {
  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}

如何将

id、id1、id2、idn

移动到根线程

尝试

没有成功，有什么想法吗

---

比尔

您可以将这些字段提取到一个

特征

，该特征本身不必扩展

表

trait BasicT {
  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}

class T1(tag: Tag) extends Table[caseClassA](tag, "A") with BasicT

class T2(tag: Tag) extends Table[caseClassB](tag, "B") with BasicT

---

您可以将这些字段提取到

特征

，该特征本身不必扩展

表

trait BasicT {
  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}

class T1(tag: Tag) extends Table[caseClassA](tag, "A") with BasicT

class T2(tag: Tag) extends Table[caseClassB](tag, "B") with BasicT

---

为了能够使用

列

，您的特质必须知道它将混合到

表

实例中：

trait BasicT {
  self: Table[_] =>

  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}

class T1(tag: Tag) extends Table[caseClassA](tag, "A") with BasicT
class T2(tag: Tag) extends Table[caseClassB](tag, "B") with BasicT

---

为了能够使用

列

，您的特质必须知道它将混合到

表

实例中：

trait BasicT {
  self: Table[_] =>

  def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

  def id1 = column[Long]("ID1", O.NotNull)

  def id2 = column[String]("ID2", O.NotNull)

  def idn = column[String]("IDn", O.NotNull)
}

class T1(tag: Tag) extends Table[caseClassA](tag, "A") with BasicT
class T2(tag: Tag) extends Table[caseClassB](tag, "B") with BasicT

---

考虑到抽象表实际上需要参数，也许抽象类是统一公共字段的更好选择

abstract class BasicTable[T](tag: Tag, tableName: String) 
    extends Table[T](tag, tableName) {

    def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

    def id1 = column[Long]("ID1")

    def id2 = column[String]("ID2")

    def idn = column[String]("IDn")

}

class T1(tag: Tag) extends BasicTable[caseClassA](tag, "A") {
    ...
    override def *  = ...
}

---

考虑到抽象表实际上需要参数，也许抽象类是统一公共字段的更好选择

abstract class BasicTable[T](tag: Tag, tableName: String) 
    extends Table[T](tag, tableName) {

    def id = column[Option[Long]]("ID", O.PrimaryKey, O.AutoInc)

    def id1 = column[Long]("ID1")

    def id2 = column[String]("ID2")

    def idn = column[String]("IDn")

}

class T1(tag: Tag) extends BasicTable[caseClassA](tag, "A") {
    ...
    override def *  = ...
}

---

这不起作用，因为

BasicT

没有

column

方法。这不起作用，因为

BasicT

没有

column

方法。