Kotlin lazy property identified as persistent entity

[maio]

Hello,

first thanks for a great library!

I encountered following problem. I have a Money data class in Kotlin and when I try to use it in my
DB entity as an @Embedded as follows:

data class Money(val value: BigDecimal, val currency: String) {
    val foo by lazy { 123 }
}

interface CardsRepositoryV1 : CrudRepository<CardsRepositoryV1.CardRow, Long> {
    @Table(value = "cards_v1")
    data class CardRow(
        ...,
        @Embedded(prefix = "effective_amount_", onEmpty = Embedded.OnEmpty.USE_NULL)
        val effectiveAmount: Money
    )
}

repository.deleteAll()

Then I get this error:

org.springframework.data.relational.core.conversion.DbActionExecutionException: Failed to execute DbAction.DeleteAll(propertyPath=effectiveAmount.foo$delegate)
Caused by: org.h2.jdbc.JdbcSQLSyntaxErrorException: Table "LAZY" not found; SQL statement:
DELETE FROM "LAZY" WHERE "LAZY"."CARDS_V1" IS NOT NULL [42102-224]

Am I doing something wrong?

PS: I'm using Spring Boot 3.2.5

Thanks,
Marian

[schauder]

Please provide a Minimimal Reproducable Example, preferable as a Github repository. Make sure to include the database, either as an in memory database or if that is not possible using Testcontainers.

[maio]

Thanks for quick reply. Here is the repository: https://github.com/maio/repro-jdbc-kotlin-lazy-embedded-problem.

./gradlew test

[mp911de]

Kotlin lazy introduces a delegate field that we discover as property. We already have precedence for Groovy's MetaClass as an exclusion rule. However, Kotlin never ceases to surprise in how they generate bytecode to achieve their goals while breaking framework support.

FWIW, here's the decompiled output:

public final class com/example/demo/Money {
     <ClassVersion=65>
     <SourceFile=DemoApplicationTests.kt>

     private final int amount;
     private final java.lang.String currency;
     private final kotlin.Lazy foo$delegate;
…

[mp911de]

For the time being, please annotate the delegated property with @delegate:org.springframework.data.annotation.Transient to exclude it from the mapping metamodel.