sprng boot jpa + redis LazyInitializationException - spring-boot

Question

I use spring boot 2.1.2 and redis as cache provider.
But now, I have a question.
In sysUser entity
#Data
#Entity
#Table(name = "sys_user")
#ToString(exclude = "roles")
#EqualsAndHashCode(callSuper = true)
#Proxy(lazy = false)
public class SysUser extends BaseEntity implements UserDetails {
// ...
/**
* 当前用户的权限
*/
#ManyToMany(fetch = FetchType.EAGER)
#JsonIgnoreProperties(value = "users")
#JoinTable(name = "sys_user_role",
joinColumns = {#JoinColumn(name = "user_id", nullable = false)},
inverseJoinColumns = {#JoinColumn(name = "role_id", nullable = false)})
private List<SysRole> roles;
// ...
}
In sysRole entity
#Data
#Entity
#Table(name = "sys_role")
#EqualsAndHashCode(callSuper = true)
#ToString(exclude = {"users", "permissions"})
#Proxy(lazy = false)
public class SysRole extends BaseEntity {
// ...
/**
* 当前角色的菜单
*/
#JsonIgnoreProperties(value = "roles")
#ManyToMany(cascade = CascadeType.MERGE, fetch = FetchType.EAGER)
#JoinTable(name = "sys_permission_role", joinColumns = #JoinColumn(name = "role_id"),
inverseJoinColumns = #JoinColumn(name = "permission_id"))
private List<SysPermission> permissions = new ArrayList<>();
/**
* 当前角色对应的用户
* 双向映射造成数据重复查询死循环问题
*/
#ManyToMany(mappedBy = "roles")
private List<SysUser> users = new ArrayList<>();
}
In SysPermission entitty
#Data
#Entity
#Table(name = "sys_permission")
#EqualsAndHashCode(callSuper = true)
#Proxy(lazy = false)
public class SysPermission extends BaseEntity {
// ...
/**
* 菜单角色
* 双向映射造成数据重复查询死循环问题
*/
#ManyToMany(mappedBy = "permissions")
private List<SysRole> roles = new ArrayList<>();
}
In sysUser service impl
#Override
#Cacheable
public SysUser loadUserByUsername(String username) {
return sysUserRepository.findFirstByUsernameAndEnabledTrue(username).orElseThrow(() ->
new UsernameNotFoundException("用户不存在")
);
}
redis config
#Bean
#Override
public CacheManager cacheManager() {
RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofHours(12))
.prefixKeysWith(applicationProperties.getName())
.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(keySerializer()))
.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(valueSerializer()))
.disableCachingNullValues();
return RedisCacheManager
.builder(RedisCacheWriter.nonLockingRedisCacheWriter(connectionFactory))
.cacheDefaults(redisCacheConfiguration)
.transactionAware()
.build();
}
#Bean(name = "redisTemplate")
public RedisTemplate<String, Object> redisTemplate() {
RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
redisTemplate.setConnectionFactory(connectionFactory);
redisTemplate.setKeySerializer(keySerializer());
redisTemplate.setHashKeySerializer(keySerializer());
redisTemplate.setValueSerializer(valueSerializer());
redisTemplate.setHashValueSerializer(valueSerializer());
return redisTemplate;
}
private RedisSerializer<String> keySerializer() {
return new StringRedisSerializer();
}
private RedisSerializer<Object> valueSerializer() {
return new GenericJackson2JsonRedisSerializer();
}
Question
When I first called loadUserByUsername,it is ok.And in redis
in json.cn
But when I secound called loadUserByUsername,it is wrong,And get exception
org.springframework.data.redis.serializer.SerializationException: Could not read JSON: failed to lazily initialize a collection, could not initialize proxy - no Session (through reference chain: cn.echocow.xiaoming.model.entity.SysUser["roles"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection, could not initialize proxy - no Session (through reference chain: cn.echocow.xiaoming.model.entity.SysUser["roles"])
at org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer.deserialize(GenericJackson2JsonRedisSerializer.java:132)
at org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer.deserialize(GenericJackson2JsonRedisSerializer.java:110)
at org.springframework.data.redis.serializer.DefaultRedisElementReader.read(DefaultRedisElementReader.java:48)
......
Caused by: com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection, could not initialize proxy - no Session (through reference chain: cn.echocow.xiaoming.model.entity.SysUser["roles"])
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:394)
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:353)
......
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection, could not initialize proxy - no Session
at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:597)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:216)
at org.hibernate.collection.internal.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:160)
at org.hibernate.collection.internal.PersistentBag.size(PersistentBag.java:287)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:302)
......
Other
I try these methods
#JsonIgnore , but it will set roles is null, I want to use this field.
Config jackson registerModule Hibernate5Module, it will set roles is null.
Use #Proxy(lazy = false), no changes.
Use #ManyToMany(fetch = FetchType.EAGER), no changes
config
spring:
jpa:
open-in-view: true
properties
hibernate:
enable_lazy_load_no_trans: true
no changes...
Use another json tools, such as gson and FastJson, but infinite loop for jpa when save cache.
Please help me, I had spent three days...But I do not resolve this question...
Thanks!
github address: XIAOMING
If do not have resolve method, maybe I must use Mybatis. But there is a lot of work.Please help me resolve this question...

Answer 1

1st. create 2 classes below
The HibernateCollectionIdResolver.class will translate HibernateCollection class into JDK collection class, so the Jackson will write json from
{
"paramA": [
"org.hibernate.collection.internal.PersistentSet",
[]
]
}
to
{
"paramA": [
"java.util.HashSet",
[]
]
}
then the method typeFromId will get JDK JavaType from the class full name above, to deserialize your json to POJO.
class HibernateCollectionIdResolver extends TypeIdResolverBase {
public HibernateCollectionIdResolver() {
}
#Override
public String idFromValue(Object value) {
//translate from HibernanteCollection class to JDK collection class
if (value instanceof PersistentArrayHolder) {
return Array.class.getName();
} else if (value instanceof PersistentBag || value instanceof PersistentIdentifierBag || value instanceof PersistentList) {
return List.class.getName();
} else if (value instanceof PersistentSortedMap) {
return TreeMap.class.getName();
} else if (value instanceof PersistentSortedSet) {
return TreeSet.class.getName();
} else if (value instanceof PersistentMap) {
return HashMap.class.getName();
} else if (value instanceof PersistentSet) {
return HashSet.class.getName();
} else {
//default is JDK collection
return value.getClass().getName();
}
}
#Override
public String idFromValueAndType(Object value, Class<?> suggestedType) {
return idFromValue(value);
}
//deserialize the json annotated JDK collection class name to JavaType
#Override
public JavaType typeFromId(DatabindContext ctx, String id) throws IOException {
try {
return ctx.getConfig().constructType(Class.forName(id));
} catch (ClassNotFoundException e) {
throw new UnsupportedOperationException(e);
}
}
#Override
public JsonTypeInfo.Id getMechanism() {
return JsonTypeInfo.Id.CLASS;
}
}
#JsonTypeInfo(
use = JsonTypeInfo.Id.CLASS
)
#JsonTypeIdResolver(value = HibernateCollectionIdResolver.class)
public class HibernateCollectionMixIn {
}
2nd. register this MixIn class to you ObjectMapper
Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
ObjectMapper mapper = new ObjectMapper();
mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.PROPERTY);
mapper.registerModule(new Jdk8Module());
mapper.registerModule(new JavaTimeModule());
mapper.registerModule(new JodaModule());
mapper.addMixIn(Collection.class, HibernateCollectionMixIn.class);
jackson2JsonRedisSerializer.setObjectMapper(mapper);
last, register your jackson2JsonRedisSerializer to your RedisCacheConfiguration.
This would be helpful, I spent 2 days researching how to solve this problem.
And I found the json type id could be rewrite...
So just override jackson typeIdResolver~
EDIT: solve deserialization issue and add some comments

Answer 2

In your code you return valueSerializer like this
private RedisSerializer<Object> valueSerializer() {
return new GenericJackson2JsonRedisSerializer();
}
But you will have to return the GenericJackson2JsonRedisSerializer with Jackson Object mapper that has Hibernate5Module or Hibernate4Module registered as a module
public ObjectMapper getMapper() {
ObjectMapper mapper = new ObjectMapper();
mapper.enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS);
mapper.enable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
// Registering Hibernate5Module to support lazy objects for hibernate 5
// Use Hibernate4Module if using hibernate 4
mapper.registerModule(new Hibernate5Module());
return mapper;
}
private RedisSerializer<Object> valueSerializer() {
return new GenericJackson2JsonRedisSerializer(getMapper());
}