How to deserialize an object stored in redis, if the classname of the stored object changes?

Question

I have stored an object in redis, say Class StorageConnection,

public void storeSecureConnection(String uniqueKey, Object storageConnection) {
        redisTemplateAdmin.opsForValue().set(uniqueKey, storageConnection);

}

Now, I have changed the className from StorageConnection to DataConnection. All the fields and UID remains intact.

It's now giving me an SerializationException on

public DataConnection getAdminDataObject(String uniqueKey) {    
        return  (DataConnection) redisTemplateAdmin.opsForValue().get(uniqueKey);
    }

Is there any trick that I can deserialize it with new className?

Edit:

Here's RedisTemplate Initialization:

@Service
public class AdminDataBaseServiceImpl{
    private RedisTemplate<String, Object> redisTemplateAdmin;
    private HashOperations hashOps;

    private AdminDataBaseServiceImpl(RedisTemplate<String, Object> redisTemplateAdmin) {
    this.redisTemplateAdmin = redisTemplateAdmin;
    hashOps=redisTemplateAdmin.opsForHash();
}

Could you add the code where `redisTemplateAdmin` is instantiated ? — Arnaud, Feb 19 '19 at 11:34

score 1 · Answer 1 · answered Feb 20 '19 at 14:33

"{\"@class\":\"org.crm.backend.repository.redis.dto.TripInfoDto\",\"tripId\":44271,\"demandUserId\":11811,\"demandUserPhoneNumber\":\"7777777777\",\"supplierId\":1223,\"supplierPhoneNumber\":\"7777777777\",\"criticalOn\":\"DEMAND\",\"loadingBucket\":430119,\"tripType\":\"RETAIL\",\"creationTime\":1548422893462}"

This is value of key in Redis in my case, to deserialise with another class I can update value in Redis for that key.

hset mapKey 44271 "{\"@class\":\"org.crm.backend.repository.redis.dto.AnotherClass\",\"tripId\":44271,\"demandUserId\":11811,\"demandUserPhoneNumber\":\"9929011689\",\"supplierId\":1223,\"supplierPhoneNumber\":\"9929014797\",\"criticalOn\":\"DEMAND\",\"loadingBucket\":430119,\"tripType\":\"RETAIL\",\"creationTime\":1548422893462}"

So just check value in your case, if you can update the class name in it's value

score 0 · Answer 2 · answered Feb 19 '19 at 13:06

0

It is not nessesary to use Serializeable. You can serialize it to a format that does not do class checking. Example of such format can be a simple byte array, it can be json it can be a more advanced serialization framework as Kryo. You can use protobuff , here is an example : https://codeclimate.com/blog/choose-protocol-buffers/

All in all I think JSON is the simplest format to go for. Good balance between performance, readibility and searchability.

answered Feb 19 '19 at 13:06

Alexander Petrov

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But I can't change my existing design. I can change the deserialization process, but we have much data that is already serialized and stored in data. I can't afford to loose that data. – Abhishek Feb 19 '19 at 13:11
Is it so difficult to migrate it ? :) There is no go around the Classname check. At least not one that I know of immediatly. – Alexander Petrov Feb 19 '19 at 13:13
But a migration should not be that difficult theoreticaly. You just need to read data through the old format and re insert it with the new serializer. – Alexander Petrov Feb 19 '19 at 13:14
Here is one stackoverflow answer that reviews exactly what I have neen saying. You can read it from another class: https://stackoverflow.com/questions/2358886/how-can-i-deserialize-the-object-if-it-was-moved-to-another-package-or-renamed – Alexander Petrov Feb 19 '19 at 13:16
I'm afraid but this can't be done. Anything which I can do by overriding RedisDeserializers? – Abhishek Feb 19 '19 at 13:22

score 0 · Accepted Answer · answered Mar 01 '19 at 05:29

I used GenericJackson2JsonRedisSerializer to serialize the object and was storing in redis. To change the class name, I used StringRedisSerializer to deserialize, changed the classname and again stored in Redis with StringRedisSerializer.

Then used, as usual, GenericJackson2JsonRedisSerializer to deserialize the object with new classname. It worked.

How to deserialize an object stored in redis, if the classname of the stored object changes?

3 Answers3