I have a class with some nullable properties ```d...

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[farzad]

I have a class with some nullable properties

data class RequestModel(
    val description: String?
)

and a validation function

fun validate(model: RequestModel): RequestModel{
    if(model.description == null) throw IllegalArgumentException("description must be non null")
    return model
}

After this validation step, I need a way to indicate non-nullability of description property.

One solution is to create a new data class which has non null propertis data class RequestModel(val description: String).
But I'm looking for a generic way to avoid creating new classes per use case.

Ideal generic solution:

fun validate(model: RequestModel): NoNullableField<RequestModel>

How can I remove nullability from properties of a c.lass with nullable properties in a generic way? Is it usefull to use some kind of kotlin compiler contract?


Link to SO question: https://stackoverflow.com/questions/59015821

[Alowaniak]

Perhaps http://oneeyedmen.com/nothing-can-save-us.html can help?

[farzad]

Yes, This technique can help. Thanks for sharing.