使用提升嵌入时如何在一个案例类字段中组合多列? [英] How to combine multiple columns in one case class field when using lifted embedding?

问题描述

我们有一个 MySQL 表，其中包含几个布尔列，用于指定用户可能具有的角色.是否可以使用 slick 的提升嵌入来编写一个结合 & 的类型映射器?将这些多列转换为案例类 User 中的一个字段，如下所示?

We have a MySQL table containing several boolean columns which specify the roles a user may have. Is it possible with slick's lifted embedding to write a type mapper which combines & transforms these multiple columns to one field in the case class User like shown below?

case class User(id: Option[Int], nickname: String, role: Seq[Role.Role])

object Users extends Table[(User)]("ask_user") {
      def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
      def nickname = column[String]("nickname")
      def is_editor = column[Boolean]("is_editor")
      def is_moderator = column[Boolean]("is_moderator")
      def is_administrator = column[Boolean]("is_administrator")
      def is_usermoderator = column[Boolean]("is_usermoderator")
      def is_usermoderator2 = column[Boolean]("is_usermoderator2")
      def is_partner = column[Boolean]("is_partner")
      def is_premium_partner = column[Boolean]("is_premium_partner")
      def is_corporate_paid = column[Boolean]("is_corporate_paid") 
    }

推荐答案

您可以使用 * 投影上的 <> 函数为用户对象提供自己的构造函数和提取器函数.像这样:

You can provide your own constructor and extractor functions for User objects to Slick using the <> function on the * projection. Something like this:

class User extends Table[User](...){
  ...
  def * = col1 ~ col2 ~ col3 ~ col4 <> (constructUser, extractUser)
}

def constructUser( col1: T1, col2: T2, col3: T3, col4: T4 )
  = User(col1, Roles(col2, col3, col4))
def extractUser( user: User ) = user match{
  case User(col1, Roles(col2, col3, col4)) =>  (col1, col2, col3, col4)
}

object Roles{
  def apply( col2: T2, col3: T3, col4: T4 ) : Set[Role]  = ...
  def unapply( roles: Set[Role] ) : Option[(T2, T3, T4)] = ...
}

另请参阅 http://slick.typesafe.com/doc/1.0.1/lifted-embedding.html#mapped-tables

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