如何将案例 class 作为变量传递给 ScalaReflection

Question

I am trying to pass a case class as a variable to ScalaReflection to get the schema.

I am able to run the code successfully with case class name where as when I assign the case class to a variable and pass that to ScalaReflection I am getting error.

Here is my code

import org.apache.spark.sql.catalyst.ScalaReflection
import org.apache.spark.sql.types.StructType

case class Emp (empId: Integer, empName: String)
val myschema = ScalaReflection.schemaFor[Emp].dataType.asInstanceOf[StructType]
println(myschema)

val empModel = Emp
val myschema2 = ScalaReflection.schemaFor[empModel].dataType.asInstanceOf[StructType]

Error: error: not found: type empModel
val myschema2 = ScalaReflection.schemaFor[empModel].dataType.asInstanceOf[StructType]

Any suggestion is helpful!

Answer 1

Type synonyms (= aliases) should be introduced with a keyword type

type empModel = Emp
val myschema2 = ScalaReflection.schemaFor[empModel].dataType.asInstanceOf[StructType]

In Scala values and types make different namespaces.

Top definitions with type (and val ) are not allowed in Scala 2, so they have to be inside some object

object App {
  type empModel = Emp
  val myschema2 = ScalaReflection.schemaFor[empModel].dataType.asInstanceOf[StructType]
}