Map an object to a hash with Spring Data Redis

Question

Say I have a User class

class User {
    private Long id
    private String username
    private String password
}

I read a few articles/tutorials regarding storing repositories with redis in hash.

However they all have one key for the whole "table", what put into redis looks like following:

user 1 {id:1,username:'',password:''}
user 2 {id:1,username:'',password:''}

they all had id as the hash key in this case.

What I wanted to achieve is to use each field as a hash key, like below:

user:1 id 1
user:1 username ''
user:1 password ''

And after quite a lot of time searching, I found Jackson2HashMapper could be the help. But there is no articles/documentations on how to use this mapper exactly.

Have anyone else faced similar situations?

Answer 1

i just use like this:

@Bean
public HashMapper<Object, byte[], byte[]> hashMapper() {
    return new ObjectHashMapper();
}

@Component
public class HashMapping<T> {
    @NonNull
    private StringRedisTemplate                stringRedisTemplate;
    @NonNull
    private HashMapper<Object, byte[], byte[]> hashMapper;

    public void writeHash(String key, T t) {
        checkNotNull(key, "hash key cannot be null");
        checkNotNull(t, "hash value cannot be null");
        stringRedisTemplate.execute((RedisCallback<Void>) connection -> {
            Map<byte[], byte[]> mappedHash = hashMapper.toHash(t);
            connection.hMSet(key.getBytes(), mappedHash);
            return null;
        });
    }

    public T loadHash(String key) {
        checkNotNull(key, "hash key cannot be null");
        Map<byte[], byte[]> loadedHash = 
stringRedisTemplate.getConnectionFactory()
                .getConnection().hGetAll(key.getBytes());
        return (T) hashMapper.fromHash(loadedHash);
    }

}