Workaround for issues with Spring-Data-Redis Jackson's serializer, described here: http://forum.springsource.org/showthread.php?140744-Problems-with-Jackson-Redis-hash-mapping-of-nulls-amp-collections

gistfile1.txt

package com.mangofactory.example;

import java.util.Map;

import lombok.SneakyThrows;

import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.type.TypeFactory;
import org.codehaus.jackson.type.JavaType;
import org.springframework.data.redis.hash.HashMapper;
import org.springframework.data.redis.hash.JacksonHashMapper;

import com.google.common.collect.Maps;

/**
 * Work-around to bug listed here:
 * http://forum.springsource.org/showthread.php?140744-Problems-with-Jackson-Redis-hash-mapping-of-nulls-amp-collections&p=453090#post453090
 * 
 * The {@link JacksonHashMapper} that ships with Spring Data Redis tries to map
 * via jackson Object --> Hash<String,Object> --> Object
 * However, this appears to fail.
 * 
 * So, as a workaround, just write the object as pure JSON, and then decode it again.
 * This gives the benefit of still using Jackson mappers (which give fine-grained, annotation
 * driven control over the serialization process).
 * 
 * @author martypitt
 *
 */
public class StringBoundJsonHashMapper<T> implements HashMapper<T, String, String> {

  private final ObjectMapper mapper;
	private final JavaType userType;
	private final JavaType mapType = TypeFactory.mapType(Map.class, String.class, String.class);

	public StringBoundJsonHashMapper(Class<T> type) {
		this(type, new ObjectMapper());
	}

	public StringBoundJsonHashMapper(Class<T> type, ObjectMapper mapper) {
		this.mapper = mapper;
		this.userType = TypeFactory.type(type);
	}

	@SuppressWarnings("unchecked") @SneakyThrows
	public T fromHash(Map<String, String> hash) {
		String json = hash.get("json");
		T result = (T) mapper.readValue(json, userType);
		return result;
	}

	@SneakyThrows
	public Map<String, String> toHash(T object) {
		String json = mapper.writeValueAsString(object);
		Map<String,String> result = Maps.newHashMap();
		result.put("json", json);
		return result;
	}
}