Check if redis key is hash or string using restTemplate - spring-boot

Question

I have Redis DB consisting of hashes and strings.
I got all keys from DB using this code:
Set<byte[]> keys = redisTemplate.getConnectionFactory().getConnection().keys("*".getBytes());
Iterator<byte[]> it = keys.iterator();
while(it.hasNext()){
byte[] data = (byte[])it.next();
String key = (new String(data, 0, data.length));
System.out.println(key);
}
from here: How to get all Keys from Redis using redis template
Since the key can be hash or string, how to determine when I can use opsForHash and opsForValue i.e. how to check if it is hash or it is a string in spring boot using restTemplate.

Answer 1

The Redis command to get the type of a key is TYPE: https://redis.io/commands/type
You can use RedisTemplate's public DataType type(K key) method to execute this: https://docs.spring.io/spring-data/redis/docs/current/api/org/springframework/data/redis/core/RedisTemplate.html#type-K-
Here's an example:
Set<byte[]> keys = redisTemplate.getConnectionFactory().getConnection().keys("*".getBytes());
Iterator<byte[]> it = keys.iterator();
while(it.hasNext()){
byte[] data = (byte[])it.next();
String key = (new String(data, 0, data.length));
DataType type = redisTemplate.type(key);
if (type == DataType.HASH) {
// ...
} else if (type == DataType.STRING) {
// ...
}
}
Edit: one more piece of advice is that you may want to use SCAN instead of KEYS * (mentioned in one answer to the SO question you linked). Scan is generally better in production since it doesn't try to get and return all keys at once.