Question

假设这样的模型：

Sub test()

Range("A5:A30").AdvancedFilter Action:=xlFilterCopy, CopyToRange:=Range("'Sheet1'!E7"), Unique:=True

For i = 7 To Cells(7, 5).End(xlDown).Row
      Cells(i, 6).Value = Application.WorksheetFunction.SumIf(Range("A:A"), Cells(i, 5),Range("B:B"))
Next i


End Sub

我希望能够发送/接收Message [PayloadKind]对象并让Avro做正确的事情。（现在它完全被困惑了！）

这种东西的Avro架构会是什么样子？我已经走到了这一步：

trait PayloadKind
trait Command extends PayloadKind
trait Event extends PayloadKind

trait Message[T <: PayloadKind] {
  val id: String
  val payload: T
}

case class Alarm(severity: Int) extends Event

case class AlarmMessage(id: String, payload: Alarm) extends Message[Event]

PayloadKind（和事件/命令）是标记特征。我如何在Avro Schema中表示它们？

Answer 1

要对此进行建模，您需要为记录和联合使用命名类型：

然后，Avro可以通过名称找出联盟内的WHICH记录类型。该名称充当子类的鉴别器。

{
  "type":"record","name":"Message","namespace":"com.tryme","fields":[
    {"name":"id","type":"string"},
    {"name":"payload","type":[ 
      {
      "type":"record","name":"Event","fields":[]
      },
      {
      "type":"record","name":"Command","fields":[]
      }
      ]
    }
  ]
}

我如何在Avro中代表Scala特征？

1 个答案: