postgresql – 如何在Scala中使用Typesafe Slick创建自定义列类
发布时间:2020-12-13 16:31:34 所属栏目:百科 来源:网络整理
导读: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 S
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) ) (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |