Query MongoDB-在查询distinct（）时出现编解码器错误

Question

我是Scala的mongodb新手。我正在尝试获取记录中的所有distinc id，并且应该获取[id1，id2，id3，...，idn]

我的代码

val mongoClient: MongoClient = MongoClient()
val db: MongoDatabase = mongoClient.getDatabase("myDB")

val collection = db.getCollection("Datalake")
val response = Await.result(collection.distinct[Double]("idWell").toFuture(), Duration(5, TimeUnit.SECONDS))
if (response != null && response.nonEmpty) {
      response.foreach(println(_))
}

我在线程“主”中得到异常org.bson.codecs.configuration.CodecConfigurationException：找不到用于double的编解码器。我是否需要在数据库连接器中配置任何内容？那个代码是正确的还是我应该用来理解未来？无论哪种方式，我都会得到相同的错误

输入数据应类似于以下内容（数组只是一个示例，记录是MongoDB中的文档）：

[
  {
    "_id": "[field id]",
    "oilFieldId": "[the id I'm using which represents an oil field id]",
    "tef":"[a number]",
    "agg":"[the field I'd like to update (currently = '')]",
    "date": "[year-month-day]"
  },
  {
    "_id": "[another field id]",
    "oilFieldId": "[the id I'm using which represents an oil field id]",
    "tef":"[a number]",
    "agg":"[the field I'd like to update (currently = '')]",
    "date": "[year-month-day]"
  },
  {
    "_id": "[another field id]",
    "oilFieldId": "[the id I'm using which represents an oil field id]",
    "tef":"[a number]",
    "agg":"[the field I'd like to update (currently = '')]",
    "date": "[year-month-day]"
  },
  ...
]

输出应为“ oilFieldId”的数组

[[1232345，135245，123155，24524，...]

Answer 1

发现错误。问题是返回值的编解码器，它实际上不是Double而是BsonInt32.type。这就是为什么在org.bson.codecs中找不到编解码器的原因

我已经完成了对理解的理解，并从Future.onComplete获得了价值。这是代码

val d = for(
      a <- collection.distinct[BsonInt32]("oilFieldId").toFuture()
    )yield a

    d.onComplete{
      case Success(element) => element.foreach{
        System.out.println(_)
      }
      case Failure(t) => System.out.println(t.getMessage)
    }