Values saved in Redis using Spring Data have weird prefixes

Question

I'm using Spring Data Redis with Kotlin but without Spring data repositories because of the shortcoming in DATAREDIS-1250. So, I created my own little repository.

interface CoroutinesRepository<T : Serializable> {
    suspend fun save(entity: T): T
    suspend fun findByIdOrNull(id: String): T?
    suspend fun deleteById(id: String)
}

and its implementation:

abstract class AbstractCoroutinesRepository<T : Serializable>(clazz: Class<T>) : CoroutinesRepository<T> {
    private val hash: String = clazz.simpleName
        .// convert class name to hyphenated string
    private val idField: Field = clazz.declaredFields
        .// find field with @Id annotation

    @Autowired
    private lateinit var redisTemplate: ReactiveRedisTemplate<Any, Any>
    @Autowired
    private lateinit var persistenceProperties: PersistenceProperties

    override suspend fun save(entity: T): T {
        val valueOps = redisTemplate
            .opsForValue()
        valueOps.set("$hash:${idField.get(entity)}", entity, getTtl(persistenceProperties))
            .awaitFirst()
        return entity
    }
    // Other methods omitted
}

used as:

@Repository
class ResponseRepositoryImpl : AbstractCoroutinesRepository<Response>(Response::class.java)

This works and the above code can set and get values from Redis. However, when I query from Redis CLI, I see:

127.0.0.1:6379> SCAN 0
1) "0"
2) 1) "\xac\xed\x00\x05t\x00\x0cuuid:test"
   2) "\xac\xed\x00\x05t\x00\x10response:test"

What is this weird string prefix? As I said, it doesn't seem to affect the retrieval, but I'm curious.

Spring Data Redis 2.3.5.RELEASE.

Answer 1

This turned out to be due the use of default JdkSerializationRedisSerializer, and I'm guessing the weirdness is the field meta information (type etc). Other Redis serializers like GenericJackson2JsonRedisSerializer don't do this, and the data is saved in a human-readable format.