如何将案例类传递给函数参数并相应地获取模式？

Question

the function which will return me the schema I made a function called getschema(MyCaseClass) which will return me the schema by encoding using Encoders.product[MyCaseClass].schema but Encoders.product is not taking that case class as a parameter.

case class Moviedata(id:Int, name:String, year:Int, rating:Double,duration:Int)

//calling the function defined in another class
val movieSchema = getSchema(Moviedata)


//this is not working
def getSchema[T](t:Class[T])={
    Encoders.product[t].schema
}

//this works when defined in the same class but how to generalize into a function
//val movieSchema = Encoders.product[Moviedata].schema 

Answer 1

Here is the working example, don't forget about the import

import scala.reflect.runtime.universe._

case class Moviedata(id:Int, name:String, year:Int, rating:Double,duration:Int)

val movieSchema = getSchema(Moviedata)

def getSchema[T <: Product : TypeTag]={
  Encoders.product[T].schema
}

Some explanations.
Encoders.product takes type parameter not a class and doesn't have arguments.

def getSchema[T]={
    Encoders.product[T].schema
}

Unfortunately, it is still not enough for the compiler, it needs to know the runtime type of your instance. Scala's way to provide it is via TypeTag trait that is added as an implicit parameter.

def getSchema[T](implicit t : TypeTag[T])={
  Encoders.product[T].schema
}

Or in a more concise way:

def getSchema[T : TypeTag]={
    Encoders.product[T].schema
}

But there is another restriction, your class must also be a Product

def getSchema[T <: Product : TypeTag]={
  Encoders.product[T].schema
}