带有json4s的phantom-dsl中JSON序列化程序的Scala类型差异错误

Question

以下代码出现以下错误。任何见解都非常感谢。不太清楚是什么原因造成的，因为我在整个应用程序中有大量其他用户定义的类型并没有导致这种行为。

如果需要更多信息才能提供指导/建议，请告诉我。

    [error] /Users/dan_mi_sun/projects/openblockchain/src/main/scala/org/dyne/danielsan/openblockchain/data/model/GenericVinModel.scala:35: type mismatch;
    [error]  found   : org.dyne.danielsan.openblockchain.data.model.VinsModel
    [error]  required: com.websudos.phantom.CassandraTable[org.dyne.danielsan.openblockchain.data.model.VinsModel,org.dyne.danielsan.openblockchain.data.entity.Vin]
    [error] Note: org.dyne.danielsan.openblockchain.data.model.ConcreteVinsModel <: org.dyne.danielsan.openblockchain.data.model.VinsModel (and org.dyne.danielsan.openblockchain.data.model.VinsModel <: com.websudos.phantom.CassandraTable[org.dyne.danielsan.openblockchain.data.model.ConcreteVinsModel,org.dyne.danielsan.openblockchain.data.entity.Vin]), but class CassandraTable is invariant in type T.
    [error] You may wish to define T as +T instead. (SLS 4.5)
    [error]   object scriptsig extends JsonListColumn[VinsModel, Vin, ScriptSig](this) {
    [error]                                                                      ^
    [error] one error found

---

import com.websudos.phantom.CassandraTable
import com.websudos.phantom.dsl._
import org.json4s._
import org.json4s.jackson.JsonMethods._
import org.json4s.jackson.Serialization
import org.json4s.jackson.Serialization.write

import scala.concurrent.Future

case class ScriptSig(asm: String,
                     hex: String)

case class Vin(txid: String,
               vout: Int,
               scriptSig: List[ScriptSig],
               sequence: Int)

sealed class VinsModel extends CassandraTable[ConcreteVinsModel, Vin] {

  implicit val formats = Serialization.formats(NoTypeHints)

  override def fromRow(row: Row): Vin = {
    Vin(
      txid(row),
      vout(row),
      scriptSig(row),
      sequence(row)
    )
  }

  object txid extends StringColumn(this)

  object vout extends IntColumn(this)

  object scriptSig extends JsonListColumn[VinsModel, Vin, ScriptSig](this) {
    override def fromJson(obj: String): ScriptSig = {
      parse(obj).extract[ScriptSig]
    }

    override def toJson(obj: ScriptSig): String = {
      write(obj)
    }

  }

  object sequence extends IntColumn(this)
}

abstract class ConcreteVinsModel  extends VinsModel  with RootConnector {

  override val tableName = "vins"

  def insertNew(v: Vin): Future[ResultSet] = insertNewVin(v).future()

  def insertNewVin(v: Vin) = {
    insert
      .value(_.txid, v.txid)
      .value(_.vout, v.vout)
      .value(_.scriptSig, v.scriptSig)
      .value(_.sequence, v.sequence)
  }
}

Answer 1

这一行：

object scriptSig extends JsonListColumn[VinsModel, Vin, ScriptSig](this)

应该是

object scriptSig extends JsonListColumn[ConcreteVinsModel, Vin, ScriptSig](this)