postgresql – 如何在Scala中使用Typesafe Slick创建自定义列类型？

我有一个带有枚举的PostgreSQL表,它由以下内容创建：

CREATE TYPE file_status AS ENUM ('new','uploading','queued','processing','done','failed');

和相关的领域

CREATE TABLE files ( ...
    status file_status NOT NULL,...
);

使用Scala 2.10和Typesafe Slick 1.0.1,我已经创建了我的Files表的映射,除了状态字段外,它的工作正常,这需要自定义的file_status类型,一个字符串.

def status = column[FileStatus]("status")

我一直在玩Slick的TypeMapper,但还是不知道如何让它工作：

sealed trait FileStatus

implicit val fileStatusMapper: TypeMapper[String] = base[FileStatus,String](
  s => s.toString,f => f(FileStatus)
)

我收到错误：类型不匹配;发现：models.Files.FileStatus.type必需：Int

为什么需要Int？是因为TypeMapper吗？我也试过了

...
f => f.toString
// type mismatch; found : String required: models.Files.FileStatus

f => f
// type mismatch; found : String required: models.Files.FileStatus

感谢您帮助我理解这种映射的任何指示.

引用文档( http://slick.typesafe.com/doc/1.0.1/lifted-embedding.html#user-defined-functions-and-types)：

// An algebraic data type for booleans
sealed trait Bool
case object True extends Bool
case object False extends Bool

// And a TypeMapper that maps it to Int values 1 and 0
implicit val boolTypeMapper = MappedTypeMapper.base[Bool,Int](
  { b => if(b == True) 1 else 0 },// map Bool to Int
  { i => if(i == 1) True else False } // map Int to Bool
)

使其适应文件状态：

sealed trait FileStatus
case object New extends FileStatus
case object Uploading extends FileStatus
...

implicit val fileStatusTypeMapper = MappedTypeMapper.base[FileStatus,String](
  {
    case New => "new"
    case Uploading => "uploading"
    ...
  },{
    case "new" => New
    case "uploading" => Uploading
    ...
  }
)

更新：

另一个不那么冗余但可能也不太清晰的版本：

sealed trait FileStatus
case object New extends FileStatus
case object Uploading extends FileStatus
...

val statusMap = Map(
    New -> "new",Uploading -> "uploading",...
)

implicit val fileStatusTypeMapper = MappedTypeMapper.base[FileStatus,String](
  statusMap,statusMap.map(_.swap)
)