Referencing value and calling methods in generic class types - spring

Question

I'm new to Kotlin coming from C#. Currently I am trying to setup a class that takes in a couple of interchangeable generic types, the internal code of this class is a spring service end-point.
I have started with something like below, however I seem to have trouble with the syntax to reference the parameters of the request body as well as calling a method, which are of the types passed in through the class constructor. Syntax of generics and reflection does not seem that straight forward and most of the Kotlin examples I have been digging up has not seem to covered precisely what I am trying to do (if even possible). The object instance of type1 will be passed in through the body parameter and the object instance of type2 should be passed in through the constructor (syntax is probably not right).
Planning to use this as a template to setup several end-points based on the same base code but with different requests and services classes.
Any help is greatly appreciated.
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation.RequestBody
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RequestMethod
import javax.validation.Valid
open class Base <T1,T2>(t1: Class<T1>, t2: Class<T2>) {
#Autowired
var type1 = t1
#Autowired
var type2 = t2
#ApiOperation(value = "API 1", response = myResponse::class)
#ApiResponses(value = *arrayOf(
ApiResponse(code = 200, message = "successful", response = CcdaResponse::class),
ApiResponse(code = 405, message = "Invalid", response = Void::class)))
#RequestMapping(
value = "/myEndPoint",
produces = arrayOf("application/json"),
consumes = arrayOf("application/json"),
method = arrayOf(RequestMethod.POST)
)
fun endpoint(
#ApiParam(value = "Options", required = true)
#Valid
#RequestBody
body: Class<T1>
): ResponseEntity<myResponse> {
val r = myResponse()
val response: ResponseEntity<myResponse>
response = ResponseEntity(r, HttpStatus.OK)
try {
//payload
val parameters = Parameters().apply {
Id1 = type1::body.Id1.get()
Id2 = type1::body.Id2.get()
Id3 = type1::body.Id3.get()
Id4 = type1::body.Id4.get()
v = type1::body.v.get()
}
//Do stuff like calling method in class of type2 passed in
val d = type2.getViewModel(parameters)
r.status = "ok"
} catch (e: Exception) {
r.message = e.toString()
r.status = "error"
} finally {
}
return response
}
}

Answer 1

The types of the parameters are passed in through the type arguments when creating an instance (the same as Java). So you do need to pass in the types themselves, adding a Class parameter just isn't the correct syntax.
I believe this is what you are looking for (omitted some code for brevity).
open class Base<T1, T2> (#Autowired var t2: T2) {
#Autowired var type1: T1? = null
fun endpoint(
#ApiParam(value = "Options", required = true) #Valid #RequestBody
body: T1
): ResponseEntity<MyResponse> {
type1 = body
}
}
Then, for instance, you can create an instance of this class with the types Int and String (for T1 and T2 respectively) in the following manner.
val t2 = "t2"
val base = Base<Int, String>(t2)
Or you can subclass the Base class with any (or none) of the types specified.
class SubBase(t2: String): Base<Int, String>(t2)