在Scala中设计避免if-else梯形图的数据帧规则引擎

sealed trait Rule
case class FilterByName(name: String) extends Rule
case class FilterByAge(minAge: Int, maxAge: Int) extends Rule
case class ModifyAge(by: Int) extends Rule

import org.apache.spark.sql.{DataFrame, SparkSession}

object RuleEngine {
  def applyRules(data: DataFrame, rules: List[Rule]): DataFrame = {
    rules.foldLeft(data) {
      case (df, FilterByName(name)) =>
        df.filter(col("name") === name)
      case (df, FilterByAge(minAge, maxAge)) =>
        df.filter(col("age") >= minAge && col("age") <= maxAge)
      case (df, ModifyAge(by)) =>
        df.withColumn("age", col("age") + by)
    }
  }
}

// 初始化SparkSession
val spark = SparkSession.builder.appName("RuleEngineExample").getOrCreate()

import spark.implicits._

// 创建示例数据
val data = Seq(
  ("Alice", 30),
  ("Bob", 25),
  ("Charlie", 35)
).toDF("name", "age")

// 定义规则列表
val rules = List(
  FilterByName("Alice"),
  ModifyAge(5)
)

// 应用规则
val result = RuleEngine.applyRules(data, rules)

result.show()