org.apache.spark.SparkException：无法执行用户定义的函数

Question

我是scala新手，我正在尝试执行以下代码：

val SetID = udf{(c:String, d: String) =>
    if( c.UpperCase.contains("EXKLUS") == true)
    {d}
    else {""}
}
val ParquetWithID = STG1
  .withColumn("ID", SetID( col("line_item"), col("line_item_ID")))

两列 (line_item和) 均按架构中的方式line_item_id定义。StringsSTG1

当我尝试运行代码时出现以下错误：

`org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1$$anonfun$2: (string, string) => string)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:370)
at org.apache.spark.sql.execution.SparkPlan$$anonfun$4.apply(SparkPlan.scala:246)
at org.apache.spark.sql.execution.SparkPlan$$anonfun$4.apply(SparkPlan.scala:240)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:803)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:803)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:319)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:283)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:70)
at org.apache.spark.scheduler.Task.run(Task.scala:86)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:274)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)

和

Caused by: java.lang.NullPointerException
    at MyTests$$anonfun$1$$anonfun$2.apply(MyTests.scala:356)
    at MyTests$$anonfun$1$$anonfun$2.apply(MyTests.scala:355)
    ... 16 more

我也尝试过c.UpperCase().contains("EXKLUS")，但遇到了同样的错误。但是，如果我只是运行一个“ if equals”语句，一切都会正常。所以我猜问题出UpperCase().contains(" ")在我的函数中，udf但我不明白问题来自哪里。任何帮助将不胜感激！

Answer 1

如果schema包含为

 |-- line_item: string (nullable = true)
 |-- line_item_ID: string (nullable = true)

然后在 if 语句中检查null应该解决问题（请注意，有toUpperCase用于字符串的方法）

val SetID = udf{(c:String, d: String) =>
  if(c != null && c.toUpperCase.contains("EXKLUS") == true)
  {d}
  else {""}
}
val ParquetWithID = STG1
  .withColumn("ID", SetID( col("line_item"), col("line_item_ID")))

我希望答案有帮助