mysql - Slick 2.1.0 和 Traits 中的外键关系

Question

所以我有一个现有的项目。这些都不是我写的，作者选择如何实现 Slick 让我有些困惑。

这是一个现有的表/光滑的类集:

case class SourcesRow(id: Long,
                      childSourceId: Long,
                      childSourceName: String,
                      parentSourceId: Long,
                      parentSourceName: String)

trait SourcesTable { this : DbProfile =>

  import profile.simple._

  class SourcesRows(tag : Tag) extends Table[SourcesRow](tag, "Sources") {
    def id = column[Long]("Id", O.PrimaryKey, O.NotNull, O.AutoInc)
    def childSourceId = column[Long]("ChildSourceId", O.NotNull)
    def childSourceName = column[String]("ChildSourceName", O.NotNull)
    def parentSourceId = column[Long]("ParentSourceId", O.NotNull)
    def parentSourceName = column[String]("ParentSourceName", O.NotNull)

    def * = (id, childSourceId, childSourceName, parentSourceId, parentSourceName) <> (SourcesRow.tupled, SourcesRow.unapply)
  }

  val sources = TableQuery[SourcesRows]

  object SourcesTable {
    def listSources()(implicit session: SessionDef) =
      sources.run
  }

}

...我们有几个像这样加载到数据库对象中

class ControlledValuesDb(override val profile: JdbcProfile) extends DbProfile
  with RestrictionsTable
  with RestrictionCategoriesTable
  with SourcesTable
  with CollectionsTable
  with SiteDestinationsTable
  with SupplementalCategoriesTable
  with ListsTable
  with ItemsTable {
...
}

现在我正在尝试添加一个具有关系的表(这些表都没有任何关系。我一直在查看 Slick 2.1 文档，看起来我需要从对象引用一个 TableQuery，但我我不太确定如何实现这一点。请参阅下面的???:

case class ItemsRow(id: Long , listId: Long, value: String)
case class ListsRow(id: Long, name: String)

trait ListsTable { this: DbProfile =>

  import profile.simple._

  class ListsRows(tag: Tag) extends Table[ListsRow](tag, "Lists") {
    def id = column[Long]("Id", O.PrimaryKey, O.NotNull, O.AutoInc)
    def name = column[String]("Name", O.NotNull)

    def * = (id, name) <> (ListsRow.tupled, ListsRow.unapply)
  }

  val lists = TableQuery[ListsRows]

  object ListsTable {

  }

}

trait ItemsTable { this: DbProfile =>

  import profile.simple._

  class ItemsRows(tag : Tag) extends Table[ItemsRow](tag, "Items") {
    def id = column[Long]("Id", O.PrimaryKey, O.NotNull, O.AutoInc)
    def listId = column[Long]("ListId", O.NotNull)
    def value = column[String]("Val", O.NotNull)
    //def list = foreignKey("fk_item_list_id", listId, ???)(_.id)

    def * = (id, listId, value) <> (ItemsRow.tupled, ItemsRow.unapply)
  }

  val items = TableQuery[ItemsRows]

  object ItemsTable {

  }

}

Answer 1

如果你想要的是有一个有关系的表

您可以按如下方式建模

class PostTable(tag: Tag) extends Table[BlogPost](tag, "posts") {
  def pid = column[Long]("pid", O.PrimaryKey, O.AutoInc)
  def author = column[String]("author") // fk of user table

  def userFK =
    foreignKey("author_fk", author, TableQuery[UserTable])(_.email, ForeignKeyAction.Restrict, ForeignKeyAction.Cascade)

  def * = (pid, author, title, content, postAt, tags) <> (BlogPost.tupled, BlogPost.unapply)
}

class UserTable(tag: Tag) extends Table[User](tag, "users") {
  def email = column[String]("email", O.PrimaryKey)
  def * = (email, password, name) <> (User.tupled, User.unapply)
}

注意PostTable中的userFK是一个fk约束TableQuery 只是一个可用于查询数据库的对象

例如，您的代码中有 valsources = TableQuery[SourcesRows]，然后您就可以执行此操作

sources.filter(_.pid === 1001L) 

这意味着从 pid = 1001 的源中选择*；

希望这有帮助 =)