Spark Scala - 如何从嵌套 JSON 构造 Scala Map？

Question

我有一个包含嵌套字段的嵌套 json 数据，我想提取它并构建一个 Scala 映射。

这是示例 JSON:

"nested_field": [
  {
    "airport": "sfo",
    "score": 1.0
  },
  {
    "airport": "phx",
    "score": 1.0
  },
  {
    "airport": "sjc",
    "score": 1.0
  }
]

我想使用 saveToES() 并构建一个 Scala Map 来将字段索引到 ES 索引中，映射如下：

 "nested_field": {
    "properties": {
      "score": {
        "type": "double"
      },
      "airport": {
        "type": "keyword",
        "ignore_above": 1024
      }
    }
  }

使用 spark.read.json("example.json") 将 json 文件读入数据帧。在这种情况下构建 Scala Map 的正确方法是什么？

感谢您的帮助！

Answer 1

您可以使用下面的示例代码来完成

import org.json4s.DefaultFormats
import org.json4s.jackson.JsonMethods.parse



  case class AirPortScores(airport: String, score: Double)
  case class JsonRulesHandler(airports: List[AirPortScores])

  val jsonString: String = """{"airports":[{"airport":"sfo","score":1},{"airport":"phx","score":1},{"airport":"sjc","score":1}]}"""

  def loadJsonString(JsonString: String): JsonRulesHandler = {
  implicit val formats: DefaultFormats.type = org.json4s.DefaultFormats
  parse(JsonString).extract[JsonRulesHandler]
}

val parsedJson: JsonRulesHandler = loadJsonString(jsonString)
parsedJson.airports.foreach(println)//you can select parsedJson.airport or scores
//below ouput
AirPortScores(sfo,1.0)
AirPortScores(phx,1.0)
AirPortScores(sjc,1.0)

Spark Scala - 如何从嵌套 JSON 构造 Scala Map？

Spark Scala - How to construct Scala Map from nested JSON?

scala

apache-spark

elasticsearch-hadoop