CallMethodViaReflection Expression

CallMethodViaReflection is an expression that represents a static method call in Scala or Java using reflect and java_method functions.

Note
 reflect and java_method functions are only supported in SQL and expression modes.
Table 1. CallMethodViaReflection’s DataType to JVM Types Mapping
DataType JVM Type

BooleanType

java.lang.Boolean / scala.Boolean

ByteType

java.lang.Byte / Byte

ShortType

java.lang.Short / Short

IntegerType

java.lang.Integer / Int

LongType

java.lang.Long / Long

FloatType

java.lang.Float / Float

DoubleType

java.lang.Double / Double

StringType

String

 
import org.apache.spark.sql.catalyst.expressions.CallMethodViaReflection
import org.apache.spark.sql.catalyst.expressions.Literal
scala> val expr = CallMethodViaReflection(
     |   Literal("java.time.LocalDateTime") ::
     |   Literal("now") :: Nil)
expr: org.apache.spark.sql.catalyst.expressions.CallMethodViaReflection = reflect(java.time.LocalDateTime, now)
scala> println(expr.numberedTreeString)
00 reflect(java.time.LocalDateTime, now)
01 :- java.time.LocalDateTime
02 +- now

// CallMethodViaReflection as the expression for reflect SQL function
val q = """
  select reflect("java.time.LocalDateTime", "now") as now
  """
val plan = spark.sql(q).queryExecution.logical
// CallMethodViaReflection shows itself under "reflect" name
scala> println(plan.numberedTreeString)
00 Project [reflect(java.time.LocalDateTime, now) AS now#39]
01 +- OneRowRelation$

CallMethodViaReflection supports a fallback mode for expression code generation.

Table 2. CallMethodViaReflection’s Properties (in alphabetical order)
Property Description

dataType

StringType

deterministic

Disabled (i.e. false)

nullable

Enabled (i.e. true)

prettyName

reflect
Note
 CallMethodViaReflection is very similar to StaticInvoke expression.

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