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)
)
