in Kotlin, entity with identifier column of type Int does not insert this column when column has value 0

[jzelenka]

Kotlin 2.1.0
spring-boot-starter-data-jdbc 3.4.0

import org.springframework.data.annotation.Id
import org.springframework.data.relational.core.mapping.Table

@Table("TEST_SIMPLE_TABLE")
data class SimpleTable(
    @Id
    var simpleId: Int,
    var name: String
) 

val simpleTable = SimpleTable(simpleId = 0, name = "something")
jdbcAggregateTemplate.insert(entity)

this generates SQL without SIMPLE_ID column and obviously fails:

INSERT INTO "TEST_SIMPLE_TABLE" ("NAME") VALUES ('something')

java.sql.SQLIntegrityConstraintViolationException: ORA-01400: cannot insert NULL into ("TEST_SIMPLE_TABLE"."SIMPLE_ID")

it is related with Kotlin's Int bytecode mapping (Int -> int, Int? -> java.lang.Integer)

• when simpleId is set to other value than 0, it works
• when simpleId is defined as Int? , it works

so Int? is workaround, but not ideal to loose nullability check.
Looks like bug to me.

[schauder]

I don't see why this should be a bug. It is clearly documented that an entity with id field of type int with value 0 is considered new and the id is expected to be generated by the database by default.

If you want the id to be generated in a different way, you may resort to an EntityCallBack

If you want to change the Entity State detection, the first link reference gives you some options.

If you want to just force an insert you may use JdbcAggregateTemplate#insert

Finally this blog article might be of some use: https://spring.io/blog/2021/09/09/spring-data-jdbc-how-to-use-custom-id-generation

[jzelenka]

You are correct, just one clarification - JdbcAggregateTemplate#insert does not help, it is actually what I tried and described above. So entity change detection also does not help, because I am already doing insert.
Thanks for the info anyway :)

[schauder]

I agree.