Configure a new serializer for spring-boot redis cache config

Question

I have been trying to change the default serializer for the spring-boot redis cache because i want to change from the Default to one of the Jackson2Json implementations. There are two implementations from the Jackson2Json library one of them is the: GenericJackson2JsonRedisSerializer, which i can use on the following bean instantiation:

@Bean
@Primary
public RedisCacheConfiguration defaultCacheConfig(ObjectMapper objectMapper) {

    return RedisCacheConfiguration.defaultCacheConfig()
        .serializeKeysWith(
            SerializationPair.fromSerializer(
                new StringRedisSerializer()
            )
        )
        .serializeValuesWith(
            SerializationPair.fromSerializer(
                new GenericJackson2JsonRedisSerializer(objectMapper)
            )
        )
        .prefixKeysWith("");
}

When i use this serializer the serialization works fine, everything is stored on the redis server, but when o try to deserialize the JSON stored on the redis server i receive the following exception:

java.util.LinkedHashMap cannot be cast to tutorial.Person with root cause

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to tutorial.Person

The cache is being used on the following way:

@Cacheable(cacheNames = "person", key = "'person:'.concat(#post.id)")
public Person findPostAuthor(Post post){
}

The serializer doesn't know how to convert from the LinkedHashMap to the Person, how can i tell him how to do it?

The other serializer i tried to work with was the Jackson2JsonRedisSerializer:

@Bean
@Primary
public RedisCacheConfiguration defaultCacheConfig(ObjectMapper objectMapper) {
    Jackson2JsonRedisSerializer<Person> serializer = new Jackson2JsonRedisSerializer<>(Person.class);
    serializer.setObjectMapper(objectMapper);
    return RedisCacheConfiguration.defaultCacheConfig()
        .serializeKeysWith(
            SerializationPair.fromSerializer(
                new StringRedisSerializer()
            )
        )
        .serializeValuesWith(
            SerializationPair.fromSerializer(
                serializer
            )
        )
        .prefixKeysWith("");
}

On this way i would have to declare a bean for each object saved on the redis cache, but i can serialize / deserialize correctly.

When i insert a JSON directly on the redis cache, i can't deserialize it with this serializer the serializer just gives me a Person object with empty name, email, and id properties. Is there a way to fix this?

If there is a way to improve my question, please let me know.

Answer 1

GenericJackson2JsonRedisSerializer assumes Jackson's default typing. When you create GenericJackson2JsonRedisSerializer with an ObjectMapper instance, then make sure to configure default typing (enableDefaultTyping(…)).

Default typing works best with non-final types and requires a consistent property name for the type across all JSON payload so Jackson can identify the appropriate type to deserialize to.

Default typing uses a dynamic type marker and if your data source (Redis instance) isn't fully trusted, then this can become a security concern.

Jackson2JsonRedisSerializer is pinned to a specific type and removes the dynamic typing risk.

Answer 2

You could use Spring Data Redis

Add dependencies:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

Enable Caching anad use Jackson2JsonRedisSerializer

package com.redis.demo.redisdemo.config;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.cache.RedisCacheWriter;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@EnableCaching
@Configuration
public class RedisConfig extends CachingConfigurerSupport {
    @Autowired
    private RedisConnectionFactory redisConnectionFactory;

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        Jackson2JsonRedisSerializer serializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        serializer.setObjectMapper(objectMapper);
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(serializer);
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(serializer);
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }

    @Bean
    public RedisCacheManager redisCacheManager(RedisTemplate redisTemplate) {
        RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(redisTemplate.getConnectionFactory());
        RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(redisTemplate.getValueSerializer()));
        return new RedisCacheManager(redisCacheWriter, redisCacheConfiguration);
    }
}

Add Cacheable annotation at method to cache in redis

@Cacheable(value = "employee", key = "#id")
    public Employee getEmployee(Integer id) {
        log.info("Get Employee By Id: {}", id);
        Optional<Employee> employeeOptional = employeeRepository.findById(id);
        if (!employeeOptional.isPresent()) {
            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Id Not foud");
        }
        return employeeOptional.get();
    }

Answer 3

I know it's been a long time since the question was asked but may be there is somebody who still need the answer.

I had the same problem and I resolve it using JdkSerializationRedisSerializerinstead of GenericJackson2JsonRedisSerializer.

My RedisCacheConfiguration bean looks like:

return RedisCacheConfiguration.defaultCacheConfig()
            .entryTtl(Duration.ofHours("your-long-value"))
            .serializeKeysWith(SerializationPair.fromSerializer(new StringRedisSerializer()))
            .serializeValuesWith(SerializationPair.fromSerializer(new JdkSerializationRedisSerializer()));