data class User(
        val name: String? = null,
        val address: String? = null,
        val phone: String? = null
)

Suppose I have a data class like above I am validating properties name, address, phone as not null So if its not null how can i change its type to NotNullable because if i use this data class in anywhere else i always have to use !! or ? despite of its already validated for null check. so that data class after validation looks like

data class User(
        val name: String,
        val address: String,
        val phone: String
)

Anybody faced this problem ?

you can use :

data class User(
        val name: String = "",
        val address: String = "",
        val phone: String = ""
)

data class RawUser(val name:String?, ...){
	fun validate():User {
	  ....
	}
}

data class User(val name:String, ....)

Yes there is a lot of couling between the 2 class. But the other side of the tradeoff is that you encode model entity lifecycle into the type system, so the compiler help you to avoid error and as dev, at any place in system code, you have garantee about the lifecycle state of the entity.

so still i have to use !! assertion while assigning to User data class properties, is there any way to assign properties or cast from String? to String @ylemoigne

I'm unsure to understand what you mean :/

@chirag Could you please show some example how you constrcut this data class and why do you need

!!