How to use Column.isin with list?

问题:

val items = List("a", "b", "c")

sqlContext.sql("select c1 from table")
          .filter($"c1".isin(items))
          .collect
          .foreach(println)

The code above throws the following exception.

Exception in thread "main" java.lang.RuntimeException: Unsupported literal type class scala.collection.immutable.$colon$colon List(a, b, c) 
at org.apache.spark.sql.catalyst.expressions.Literal$.apply(literals.scala:49)
at org.apache.spark.sql.functions$.lit(functions.scala:89)
at org.apache.spark.sql.Column$$anonfun$isin$1.apply(Column.scala:642)
at org.apache.spark.sql.Column$$anonfun$isin$1.apply(Column.scala:642)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
at scala.collection.mutable.WrappedArray.foreach(WrappedArray.scala:35)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:245)
at scala.collection.AbstractTraversable.map(Traversable.scala:104)
at org.apache.spark.sql.Column.isin(Column.scala:642)

Below is my attempt to fix it. It compiles and runs but doesn't return any match. Not sure why.

val items = List("a", "b", "c").mkString("\"","\",\"","\"")

sqlContext.sql("select c1 from table")
          .filter($"c1".isin(items))
          .collect
          .foreach(println)

回答1:

According to documentation, isin takes a vararg, not a list. List is actually a confusing name here. You can try converting your List to vararg like this:

val items = List("a", "b", "c")

sqlContext.sql("select c1 from table")
          .filter($"c1".isin(items:_*))
          .collect
          .foreach(println)

Your variant with mkString compiles, because one single String is also a vararg (with number of arguments equal to 1), but it is proably not what you want to achieve.

回答2:

It worked like this in Java Api (Java 8)

.isin(sampleListName.stream().toArray(String[]::new))));

sampleListName is a List

回答3:

As Tomalak has mentioned it :

isin(java.lang.Object... list)
A boolean expression that is evaluated to true if the value 
of this expression is contained by the evaluated values of the arguments.

Therefore, you just could fix this making the following change :

val items = List("a", "b", "c").map(c => s""""$c"""")