Exclude a Kotlin data class property/field from serialization/deserialization using gson

Question

I am trying to exclude a Kotlin property from deserialization using gson. I have tried different methods from annotating the property with @Transient to creating a custom annotation strategy (specifying the strategy in the gson builder of course), but nothing seems to be working, as the property keeps getting null instead of the value I initialized the property with.

I have not tried using the @Expose annotation, but I do not want to annotate other fields with @Expose

Please, how can I achieve this please using gson + Kotlin?

Answer 1

@Transient worked for me.

@Transient lateinit var bar: SomeCustomType

Per @Transient definition:

Marks the JVM backing field of the annotated property as transient, meaning that it is not part of the default serialized form of the object.

Answer 2

I have yet to find a more elegant solution, but for now, I've given the property a different name and removed it from the class's default constructor.

{
    "fName": "Bilbo"
    "lName": "Baggins"
}

data class Person(val fName: String) {
    lateinit var lNameObj: String
}

Then I can assign lNameObj in my custom deserializer.

Answer 3

data class Foo (
    @Expose(deserialize = false) val bar: Bar
)