[SOLVED] Sealed data classes not considering parent property in equals

Sealed data classes not considering parent property in equals

Consider the following:

sealed class MySealedClass(val guid: String = UUID.randomUUID().toString()) {
    data class MyDataClass(var title: String) : MySealedClass()
    data class MyDataClass2(var something: String) : MySealedClass()
}

val instance1 = MySealedClass.MyDataClass("hello")
val instance2 = MySealedClass.MyDataClass("hello")

Timber.i("instance1 guid: ${instance1.guid}")
Timber.i("instance2 guid: ${instance2.guid}")
Timber.i("are instances equal? ${instance1 == instance2}")

// Output:
instance1 guid: <removed>eb
instance2 guid: <removed>a6 // note that instance 2 GUID is different!
are instances equal? true   // yet the instances are considered equal

Seems like the guid property from the parent class MySealedClass is not considered in the equals() method generated for the data classes. How can I make sure that it is considered? Is there any way without touching the generated equals() method?

Solution

Data classes in Kotlin use only properties listed in the primary constructor, when equals/hashCode/toString generated (see documentation). So, to include the guid into generated methods implementation, pass it as a constructor parameter:

data class MyDataClass(
    var title: String, 
    override val guid: String = UUID.randomUUID().toString()
) : MySealedClass()