使用Slick

Question

我正在尝试获取消息列表，包括所述消息的所有附件。到目前为止，我不得不使用从AttachmentsEntity到MessageEntity的外键来滑动实体：MessageEntity和AttachmentEntity。

我试图将这两个结果分组，然后以一种方式将每个消息与附件列表选项相关联

val messages = TableQuery[MessageLifted]

val messagesAndAttachmentsLeftJoin = messages joinLeft piecesJointes on {
    (_msg, _pj) => _msg.id === _pj.idMessage
  }

val messagesAndAttachments = messagesAndAttachmentsLeftJoin .groupBy(_._1).map{ case (msg, req) => (msg, req.map(_._2)) }


def getMessagesConversation(isDemo: Boolean,
                              identifUser: String,
                              conversationId: String)(implicit messages: Messages): Future[List[Message]] = dbRepository.perform(isDemo) {
    val messages = messagesAndAttachments.result.map(_.map {
      case (message) => {
        entityToMessage(message)
      }
    }.toList)

我希望有一个类型为List [tuple2（Message，List [Attachment]）]的对象，但出现以下错误：

/root/projects/digifact/server/digifact/app/repositories/digifact/messagerie/MessagerieRepository.scala:146: No matching Shape found.
[error] Slick does not know how to map the given types.
[error] Possible causes: T in Table[T] does not match your * projection,
[error]  you use an unsupported type in a Query (e.g. scala List),
[error]  or you forgot to import a driver api into scope.
[error]   Required level: slick.lifted.FlatShapeLevel
[error]      Source type: (repositories.digifact.documentation.MessageLifted, slick.lifted.Query[slick.lifted.Rep[Option[repositories.digifact.documentation.PieceJointeLifted]],Option[repositories.digifact.documentation.PieceJointeEntity],[+A]Seq[A]])
[error]    Unpacked type: T
[error]      Packed type: G
[error]   private val messagesAndAttachments = messagesAndAttachmentsLeftJoin.groupBy(_._1).map{ case (msg, req) => (msg, req.map(_._2))}

有帮助吗？