my class has a `val expensiveProperty: Foo? by lazy { ... }`. I'd like to have it skipped by `kotlin...

# getting-started

[y]

my class has a val expensiveProperty: Foo? by lazy { ... }. I'd like to have it skipped by kotlinx serialization and deserialization. is this possible?

[Johan]

You can use @Transient
https://kotlinlang.org/api/kotlinx.serialization/kotlinx-serialization-core/kotlinx.serialization/-transient/

[Johan]

https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/basic-serialization.md#transient-properties

[y]

this gives me Property does not have backing field which makes it non-serializable and therefore @Transient is redundant
but (and I could be wrong here!) I do observe this new lazy initializer getting called by serialization

[y]

on second glance, might be our own code interacting with this.

[Johan]

I think this should work

@Serializable
class Bar {
    @delegate:Transient
    val expensiveProperty: Foo by lazy { Foo() }
}

data class Foo(val value : String = "")
fun main() {
    val bar = Json.decodeFromString<Bar>("""{}""")
    val barJson = Json.encodeToString(bar)
    println(barJson)
    println(bar.expensiveProperty.value)
}

[asdf asdf]

If you have a delegated field / field with a getter, it is already skipped by kotlinx serialization, so @Transient isn’t needed. You can just keep the code as it is and the property won’t be serialized

[y]

yeah, that's what I gathered. so it must be our custom deserialization shenanigans