Spring + Mongodb的ID為空

Question

我正在使用Spring + MongoDB進行學術項目

我有三個文件

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;

...

}

還有一個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

在這里，我不知道為什么角色和用戶實例可以自動生成，而userrole無法生成。 控制台向我返回了一個異常，即Id為NULL，無法引用。

我對此並不陌生，希望有人能給我答案。

謝謝。

Answer 1

似乎您正在調用userRoleRepository.save(ur) ，以防數據庫中不存在具有提供的用戶名的User ， 並且實際上沒有將該User存儲在數據庫中。

我相信您應該以一種方式來重新組織代碼，以先存儲User ，然后再使用該User集存儲UserRole 。

換句話說（代碼？），您可以在UserServiceImpl嘗試執行以下操作：

@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;
}

如您所見，我僅對呼叫進行了重新排序-首先存儲了User ，然后轉到了該User的userRoles 。