Getting 'ClassCastException' when using kotlin-faker with Generics Type about kotlin-faker HOT 9 CLOSED

Of course, I would like to contribute to this revision. I will try to fix this part.

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Of course, I would like to contribute to this revision. I will try to fix this part.

Great! Let me know if you need any help then.

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Hi @serpro69
Right, I have a workaround for this issue
Example in below; it's work for me:

data class BaseResponse<T>(
    val code: ResponseCode = ResponseCode.OK,
    val message: String = "",
    val error: String = "",
    val timestamp: ZonedDateTime = ZonedDateTime.now(),
    val data: T? = null,
    val status: String = ""
)

data class Car(
    val type: String = "",
    val color: String = "",
    val availableDate: ZonedDateTime = ZonedDateTime.now()
)

object CarMock {

    fun carSuccess(faker: Faker): BaseResponse<Car> {
        return BaseResponse(
            code = ResponseCode.OK,
            message = faker.lorem.punctuation(),
            status = "SUCCESS",
            data = getCar(faker)
        )
    }

   private fun getCar(faker: Faker): Car {
        return faker.randomProvider.randomClassInstance {
            typeGenerator<ZonedDateTime> {
                ZonedDateTime.now()
            }
        }
    }
}

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Yeah, I would do something similar myself :) I guess it's currently the only way to go about it due to how JVM deals with generics. I'm adding this to docs and closing the issue for now, but feel free to re-open if you find out how this can be solved in a better fashion.
Thanks!

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Hi @mandanai , thanks for opening the issue.
Yeah, I don't think I've ever tested generics with randomClassInstance generation.
I will try to reproduce this and will look into how this can be fixed (I'm not sure if I have much time this month, but I will have some free time in July for sure). Unless you'd like to contribute a fix yourself?

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@serpro69 At RandomClassProvider.kt from this it.type.classifier, I got T (KTypeParemeterImpl). How do I know the class type from the generic type, Do you have any ideas?

And for this line cast as KClass<*>, an exception event will occur.

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Hi @mandanai ,

I do not think it's possible to get the class type from generic type; you have no type information for T because JVM erases the type information. Though kotlin might have some tricks up it's sleeve that could help solve this. What first comes to mind is reified type parameters, but that of course only works with inline functions (at least for now)

I'm on vacation currently, with limited access to internet. But I'll try to search around once I'm back if you don't find an answer to this yourself by then.
I do suspect it might not be possible to fix this with current limitations of generic types.

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Hi @serpro69
Many thanks, I tried to find many ways but still haven't found the solution to this problem and if applied I can not use randomClassInstance directly with that Class; I use a separate randcomClassInstance and assign values ​​to a generic type instead.

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I use a separate randcomClassInstance and assign values ​​to a generic type instead.

Does this mean you have a "workaround" for this issue, @mandanai ?
If so, we should at least document how to work around this issue until generic properties in classes are properly supported with randomClassInstance

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