我正在与Spring + MongoDB一起进行学术项目
我有三个文档
User.java
@Document
public class User implements UserDetails, Serializable {
private static final long SerialVersionUID = 147147L;
@Id
private String id;
private String username;
private String password;
private String firstname;
private String lastname;
private String email;
private String phone;
private boolean enable = true;
private Set<UserRole> userRoles = new HashSet<>();
...
}
Role.java
@Document
public class Role implements Serializable {
private static final long SerialVersionUID = 456456L;
@Id
private String id;
private String name;
...
}
UserRole.java
@Document(collection = "user_roles")
public class UserRole implements Serializable {
private static final long SerialVersionUID = 789789L;
@Id
private String id;
@DBRef
private User user;
@DBRef
private Role role;
private String name;
...
}
还有一个UserServiceImpl.java
@Service
public class UserServiceImpl implements UserService {
private static final Logger LOG = LoggerFactory.getLogger(UserService.class);
@Autowired
UserRepository userRepository;
@Autowired
RoleRepository roleRepository;
@Autowired
UserRoleRepository userRoleRepository;
@Override
public User createUser(User user, Set<UserRole> userRoles) {
User localUser = userRepository.findByUsername(user.getUsername());
if(localUser != null) {
LOG.info("User with username {} already exist. Nothing will be done. ", user.getUsername());
} else {
for (UserRole ur : userRoles) {
roleRepository.save(ur.getRole());
//here is the problem: the userrole instance created cannot generate Id
userRoleRepository.save(ur);
}
user.getUserRoles().addAll(userRoles);
localUser = userRepository.save(user);
}
return localUser;
}
}
和DemoApplication.java
@SpringBootApplication
public class DemoApplication implements CommandLineRunner {
@Autowired
UserService userService;
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
@Override
public void run(String... args) throws Exception {
User user1 = new User();
user1.setFirstname("John");
user1.setLastname("Adams");
user1.setUsername("j");
user1.setPassword(SecurityUtility.passwordEncoder().encode("p"));
user1.setEmail("JAdams@gmail.com");
Set<UserRole> userRoles = new HashSet<>();
Role role1 = new Role();
role1.setName("ROLE_USER");
UserRole userRole1 = new UserRole();
userRole1.setRole(role1);
userRole1.setUser(user1);
userRoles.add(userRole1);
userService.createUser(user1, userRoles);
}
和ExceptionStackTrack
java.lang.IllegalStateException: Failed to execute CommandLineRunner
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:821) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:802) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:341) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
at com.example.demo.DemoApplication.main(DemoApplication.java:22) [classes/:na]
Caused by: org.springframework.data.mapping.MappingException: Cannot create a reference to an object with a NULL id.
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.createDBRef(MappingMongoConverter.java:936) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writePropertyInternal(MappingMongoConverter.java:554) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeAssociation(MappingMongoConverter.java:517) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeProperties(MappingMongoConverter.java:494) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:481) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:455) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.write(MappingMongoConverter.java:399) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.write(MappingMongoConverter.java:78) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.MongoTemplate.toDocument(MongoTemplate.java:1071) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.MongoTemplate.doSave(MongoTemplate.java:1254) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.core.MongoTemplate.save(MongoTemplate.java:1202) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.mongodb.repository.support.SimpleMongoRepository.save(SimpleMongoRepository.java:82) ~[spring-data-mongodb-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:377) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:641) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:605) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:590) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.0.10.RELEASE.jar:2.0.10.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at com.sun.proxy.$Proxy73.save(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:197) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.0.9.RELEASE.jar:5.0.9.RELEASE]
at com.sun.proxy.$Proxy73.save(Unknown Source) ~[na:na]
at com.example.demo.Service.Impl.UserServiceImpl.createUser(UserServiceImpl.java:42) ~[classes/:na]
at com.example.demo.DemoApplication.run(DemoApplication.java:46) [classes/:na]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:818) [spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
... 5 common frames omitted
在这里，我不知道为什么角色和用户实例可以自动生成，而userrole无法生成。控制台向我返回了一个异常，即Id为NULL，无法引用。
我对此很陌生，希望有人能给我答案。
谢谢。
答案 0 :(得分：0)
在实际存储此userRoleRepository.save(ur)之前，如果和数据库中不存在具有提供的用户名的User，您似乎正在调用User在里面。
我相信您应该重新组织代码，以便先存储User，然后再存储带有UserRole集的User。
换句话说（代码？），您可以在UserServiceImpl中尝试执行以下操作：
@Override
public User createUser(User user, Set<UserRole> userRoles) {
User localUser = userRepository.findByUsername(user.getUsername());
if(localUser != null) {
LOG.info("User with username {} already exist. Nothing will be done. ", user.getUsername());
} else {
user.getUserRoles().addAll(userRoles);
localUser = userRepository.save(user);
for (UserRole ur : userRoles) {
roleRepository.save(ur.getRole());
userRoleRepository.save(ur);
}
}
return localUser;
}
如您所见，我仅对呼叫进行了重新排序-首先存储User，然后为此userRoles进入User。