Question

我需要帮助使用幻像和cassandra实现通知模型。我到目前为止做了什么：

import java.util.UUID

import com.websudos.phantom.dsl._
import com.websudos.phantom.connectors.Connector
import org.joda.time.DateTime

import scala.concurrent.Future

case class Notification(
  id:           UUID,
  userId:       UUID,
  timestamp:    DateTime,
  read:         Boolean,
  actionUser:   List[String],
  verb:         String,
  itemId:       UUID,
  collectionId: String
)

sealed class NotificationTable extends CassandraTable[NotificationTable, Notification] {

  object id extends UUIDColumn(this) with ClusteringOrder[UUID] with Ascending

  object userId extends StringColumn(this) with PartitionKey[String]

  object timestamp extends DateTimeColumn(this) with ClusteringOrder[DateTime] with Descending

  object read extends BooleanColumn(this)

  object actionUser extends ListColumn[NotificationTable, Notification, String](this)

  object verb extends StringColumn(this)

  object itemId extends UUIDColumn(this)

  object collectionId extends StringColumn(this)

  def fromRow(row: Row): Notification =
    Notification(
      id(row),
      userId(row),
      timestamp(row),
      read(row),
      actionUser(row),
      verb(row),
      itemId(row),
      collectionId(row)
    )
}

object NotificationTable extends NotificationTable with Connector {

  override def keySpace: String = "test"
  implicit val keyspace: com.websudos.phantom.connectors.KeySpace = com.websudos.phantom.connectors.KeySpace("test")
  def insertItem(item: Notification): Future[ResultSet] =
    insert
      .value(_.id, item.id)
      .value(_.userId, item.userId)
      .value(_.timestamp, item.timestamp)
      .value(_.read, item.read)
      .value(_.actionUser, item.actionUser) 
      .value(_.verb, item.verb)
      .value(_.itemId, item.itemId)
      .value(_.collectionId, item.collectionId)
      .future()
}

不知何故，我必须定义两个keyspaces，一个用于RootConnector，一个用于insert语句。这足够接近：this example ,.但是，我的代码没有编译。我知道他们在那里使用抽象类，因此它编译。</ p>

我的问题是如何使用该抽象类？我想从另一个scala源调用insert语句。

Answer 1

尝试：

import java.util.UUID

import com.websudos.phantom.dsl._
import com.websudos.phantom.connectors.Connector
import org.joda.time.DateTime

import scala.concurrent.Future

case class Notification(
  id:           UUID,
  userId:       UUID,
  timestamp:    DateTime,
  read:         Boolean,
  actionUser:   List[String],
  verb:         String,
  itemId:       UUID,
  collectionId: String
)

//use normal class
class NotificationTable extends CassandraTable[NotificationTable, Notification] {

  object id extends UUIDColumn(this) with ClusteringOrder[UUID] with Ascending

  object userId extends StringColumn(this) with PartitionKey[String]

  object timestamp extends DateTimeColumn(this) with ClusteringOrder[DateTime] with Descending

  object read extends BooleanColumn(this)

  object actionUser extends ListColumn[NotificationTable, Notification, String](this)

  object verb extends StringColumn(this)

  object itemId extends UUIDColumn(this)

  object collectionId extends StringColumn(this)

  def fromRow(row: Row): Notification =
    Notification(
      id(row),
      userId(row),
      timestamp(row),
      read(row),
      actionUser(row),
      verb(row),
      itemId(row),
      collectionId(row)
    )
}

//use abstract
abstract class NotificationTable extends NotificationTable with Connector {

  def insertItem(item: Notification): Future[ResultSet] =
    insert
      .value(_.id, item.id)
      .value(_.userId, item.userId)
      .value(_.timestamp, item.timestamp)
      .value(_.read, item.read)
      .value(_.actionUser, item.actionUser) 
      .value(_.verb, item.verb)
      .value(_.itemId, item.itemId)
      .value(_.collectionId, item.collectionId)
      .future()
}

Answer 2

您错过了在那里使用RootConnector而不是随机Connector特征的事实。该类是抽象的原因是因为它只应在Database对象内实例化。

有关详情，请查看this tutorial，但简而言之，请注意RootConnector mixin：

abstract class ConcreteNotificationTable extends
  NotificationTable with RootConnector

然后：

class MyDatabase(val connector: KeySpaceDef) extends Database(connector) {
  // And here you inject the real session and keyspace in the table
  object notifications extends ConcreteNotificationsTable with connector.Connector
}

然后你做这样的事情：

object MyDatabase extends MyDatabase(ContactPoint.local.keySpace("my_app"))

来自其他所有源文件：

val notification = Notification(id, //etc...)
MyDatabase.notifications.insertItem(someNotification)

甚至可以更好地分离关注点，如教程中所示：

trait DbProvider extends DatabaseProvider {
  def database: MyDatabase
}
trait ProductionDbProvider extends DbProvider {
  // this would now point to your object
  override val database = MyDatabase
}

然后，每个需要数据库的地方都需要混合DbProvider或直接ProductionDbProvider。阅读教程以获取更多详细信息，这不是一个非常简单的主题，所有细节都已存在。

幻影1.25.4与卡桑德拉

2 个答案: