fixed.scala

//        implicit val chunkStateType = MappedColumnType.base[ChunkState,String](
//          { cs:ChunkState => cs.toString},
//          { s: String => ChunkState.valueOf(s).get}
//        )
        val query =  
          userDistributionQuery.leftJoin(ChunkTable.query.filter { c => c.state === (ChunkState.ASSIGNED:ChunkState) } )
            .on { case ((u_id, d_id), c) => c.distributionId === d_id && c.transcriberId === u_id }
            .map { case ((u_id, d_id), c) => c.id.? }