Scala Generics - Overloaded method - spring

Question

Considering the given code:
val repository =
context.getBean(
Introspector.decapitalize(t.getClass.getSimpleName).replace("C", "E").concat("Repository"))
and that my repositories have a String as Serializable.
I'm trying to do the following:
repository.asInstanceOf[ElasticsearchRepository[_, String]].save(getObject(t))
This one works fine:
repository.asInstanceOf[ElasticsearchRepository[_, String]].findAll()
But I don't know how to put that above to work.
Assuming the method getObject(t) is retuning the correct object to be persisted and since it's a Spring Data Repository, there are 2 save method. One that accept a single entity and another for a list of entities and it says overloaded method value save.
What I have tried so far:
I saw in another thread to force the method with a type, something like this:
repository.asInstanceOf[ElasticsearchRepository[_, String]].save(getObject(t) : TYPE)
This is ok if I knew the type and also my method getObject should return that same type.
Here is my getObject method which I return the object itself without any specific type:
#throws[IOException]
def getObject[T](t : T) = {
objectMapper.readValue(objectMapper.writeValueAsString(t), getClazz(t))
}
So I was trying to get the type like this:
val m = Manifest.classType(getClazz(t))
type TYPE = m.type
Looks good if I force my object to this type using getObject(t) : TYPE but I don't know how to use this same type in my getObject method to be returned.
Anyway, I don't even know if this is the best approach to do this, invoking a generic repository and save a generic object.
Just to understand what I'm trying to do, I'm using a aspect to intercept a Cassandra entity to be persisted, then get it and turn into a ElasticSearch entity to save a json(thats why the getObject(t)) and replicate into ElasticSearch.
Here is the full aspect class:
#Component
#Aspect
class ElasticAop {
#Autowired val context : ApplicationContext = null
val objectMapper : ObjectMapper = new ObjectMapper()
#Pointcut("execution(* com.test.service.cassandra.*.post(..)) && args(t)")
def getPointcutPost[T](t : T) : Unit = {}
#throws[Throwable]
#Before("getPointcutPost(t)")
def elasticSaveAspect[T](joinPoint: JoinPoint, t: T) = {
val m = Manifest.classType(getClazz(t))
type TYPE = m.type
val repository =
context.getBean(
Introspector.decapitalize(t.getClass.getSimpleName).replace("C", "E").concat("Repository"))
repository.asInstanceOf[ElasticsearchRepository[_, String]].findAll()
repository.asInstanceOf[ElasticsearchRepository[_, String]].save(getObject(t))
}
#throws[ClassNotFoundException]
def getClazz[T](t : T) = {
val className = t.getClass.getName.replace("cassandra", "elastic").replace("C", "E")
Class.forName(className)
}
#throws[IOException]
def getObject[T](t : T) = {
objectMapper.readValue(objectMapper.writeValueAsString(t), getClazz(t))
}
}
EDITED
Even setting up a type return in my getObject to Address and then setting the save method as follow save(getObject(t) : Address) give me the same overloaded error.
EDITED
I just figured out it's a limitation and a possible work around is to create a factory or something like this.
Then I created a service with a saveOrUpdate method:
trait ElasticGenericService[T <: ElasticGenericKey, R <: ElasticsearchRepository[T, String]] {
var r : R = _
def saveOrUpdate(t: T) = r.save(t)
}
and now I'm getting a cast exception:
java.lang.ClassCastException: Address cannot be cast to scala.runtime.Nothing$

Answer 1

What i can see here:
getObject[T](t : T) returns existential type _1 and actually kills all type checks, as you choosing the class in runtime
ElasticsearchRepository[_, String].save require existential type _2 to be passed to the save method, so _1 doesn't fit
Possible solution:
repository.asInstanceOf[ElasticsearchRepository[Any, String]].save(getObject(t).asInstanceOf[Any]) //getClass will work with runtime class instead of Any, so should be fine
Another solution (saving existential type):
def getObject[T](t : T) = {
objectMapper.readValue(objectMapper.writeValueAsString(t), getClazz(t)).asInstanceOf[T]
} //assuming T is an existential - it will return same existential as you passed