Hey question: I'm having trouble coding up a sprin...

# announcements

[Brian Trezise]

Hey question: I'm having trouble coding up a spring-data-redis transaction, wondering if anyone can help me out

I'm working from an example in Java but the normal ways of converting to Kotlin aren't working: https://docs.spring.io/spring-data/data-redis/docs/current/reference/html/#tx

Specifically, here's the java code example:

-.java

[Brian Trezise]

To simplify things I split out the callback to try to code it up. Kotlin seems to be struggling with the generics. I got this to compile (finally, after spending about half a day on it), but it is really ugly

val callback = object : SessionCallback<List<Any>> {
override fun <K: Any, V: Any> execute(operations: RedisOperations<K, V>?): List<Any> {
operations!!.multi()
operations.opsForValue().set(record.userId as K, record as V)

return operations.exec()
}
}

[Brian Trezise]

Also here's the interface for SessionCallback:

public interface SessionCallback<T> {
<K, V> T execute(RedisOperations<K, V> var1) throws DataAccessException;
}

[Brian Trezise]

Note all the replies on this are from me adding clarifying details

[phldavies]

I had a similar issue with the redis API and resolved it with an extension function on the RedisOperations<K, V> interface. This should show you the approach:

@Component
class MyRedisComponent(private val redisTemplate: StringRedisTemplate) {
    fun addStuffWithExt() {
        val txResults = redisTemplate.executeSession { operations ->
            operations.multi()
            operations.opsForSet().add("key", "value1")
            operations.exec()
        }
    }
}

fun <K : Any, V : Any, T : Any?> RedisOperations<K, V>.executeSession(session: (RedisOperations<K, V>) -> T): T? =
    execute(object : SessionCallback<T> {
        @Suppress("UNCHECKED_CAST")
        override fun <K2 : Any?, V2 : Any?> execute(operations: RedisOperations<K2, V2>): T =
            session(operations as RedisOperations<K, V>)
    })

[Brian Trezise]

Thanks