How to get KClass of generic classes like BaseResponse<Iterable<User>>

Question

If I try to get

BaseResponse<Iterable<User>>::class

I get error error only classes are allowed on the left hand side of class literal. I have searched and still not found how to get generic classes's type in kotlin.

Answer 1

You can't -KClass can only describe the class BaseResponse, and you can get a KClass instance that does that with BaseResponse::class.

What you have however, BaseResponse<Iterable<User>>, is a concrete type, which you can be represented as a KType instance. KType instances can be created, for example, with the createType function. This would look something like this:

// User
val userType = User::class.createType()
// Iterable<User>
val iterableOfUserType = Iterable::class.createType(arguments = listOf(KTypeProjection.invariant(userType)))    
// BaseResponse<Iterable<User>>
val responseType = BaseResponse::class.createType(arguments = listOf(KTypeProjection.invariant(iterableOfUserType)))

I made the choice of making the type parameters both invariant, there's also factory methods in KTypeProjection to create covariant or contravariant types, as you need them.