[SOLVED] Lettuce: AWS Elasticache: JSON MGET behaviour

Lettuce: AWS Elasticache: JSON MGET behaviour

We are using Lettuce java client to connect to AWS Elasticache (Valkey engine, Serverless, version 8.0) from Java springboot application (JDK 17 & springboot version 3.2.5)

Below is the method where I am trying to read multiple keys from elasticache using jsonMGet().

public List<JsonValue> readMultipleKeys(List<String> keys) {

        RedisAsyncCommands<String, String> async = null;
        try {
            async = redisCacheClient.connect().async();
            return async.jsonMGet(JsonPath.ROOT_PATH, keys.toArray(new String[0])).get();
        } catch (Exception e) {
            log.error("Exception while reading multiple keys from Cache: " + e.getMessage());
            return null;
        }
    }

Everything works perfectly fine as long as all the keys from the input list are present in Cache. But if any key (lets say 1 out of 100 input keys) doesn't exist in cache, it is throwing below error and not returning any other values.

Exception while reading from Cache: java.lang.NullPointerException: Cannot invoke "java.nio.ByteBuffer.remaining()" because "bytes" is null

I want the method to return all the keys that are PRESENT in cache and ignore the keys that doesn't exist.

Solution

EDIT: This seems to be addressed in Lettuce 6.5.5 and later

A NullPointerException is almost certainly a bug.

I've taken the liberty to create one in the GitHub tracker for you: https://github.com/redis/lettuce/issues/3241

I suggest we continue the conversation there.