Caching Java 8 Optional with Spring Cache

Question

I have a method:

@Cacheable(key = "#jobId")
public Optional<JobInfo> getJobById(String jobId) {
    log.info("Querying for job " + jobId);
    counterService.increment("queryJobById");
    Job job = jobsRepository.findOne(jobId);
    if (job != null) {
        return Optional.of(createDTOFromJob(job));
    }
    return Optional.empty();
}

When I am trying to retrieve the cached item I am getting the following exception:

2016-01-18 00:01:10 ERROR [trace=,span=] http-nio-8021-exec-2 [dispatcherServlet]:182 - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.data.redis.serializer.SerializationException: Cannot serialize; nested exception is org.springframework.core.serializer.support.SerializationFailedException: Failed to serialize object using DefaultSerializer; nested exception is java.lang.IllegalArgumentException: DefaultSerializer requires a Serializable payload but received an object of type [java.util.Optional]] with root cause java.lang.IllegalArgumentException: DefaultSerializer requires a Serializable payload but received an object of type [java.util.Optional]

Answer 1

Just implement the Serializable interface in your DTO

@Document(collection = "document_name")
public class Document implements Serializable {

    private static final long serialVersionUID = 7156526077883281623L;