mappedBy 引用带有注释的未知目标实体属性

【问题标题】：mappedBy reference an unknown target entity property with annotationmappedBy 引用带有注释的未知目标实体属性
【发布时间】：2017-11-13 00:02:19
【问题描述】：

我尝试将 Observable 及其观察者存储到数据库中。我在执行期间收到

org.hibernate.AnnotationException: mappedBy 引用了一个未知的目标实体属性

当然，我用谷歌找到了一些好的答案。

所以我在注解中添加了mappedBy、targetEntity、fetch和cascade。

但我仍然遇到同样的错误。到目前为止，我实际上尝试了所有我可以在谷歌上找到的东西，但都没有成功。这可能只是一个小想法，我希望你能帮助我。 （我用的是 Spring Boot）

ObservableImpl 

@Entity
public class ObservableImpl extends Observable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;
    @OneToMany(mappedBy = "oservableImpl", targetEntity = ObserverImpl.class, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    List<ObserverImpl> observerList = new LinkedList<>();


    public ObservableImpl(String name) {
        this.name = name;
    }

    protected ObservableImpl() {
    }

    @Override
    public synchronized void addObserver(Observer o) {
        super.addObserver(o);
        observerList.add((ObserverImpl) o);
    }

    @Override
    public synchronized void deleteObserver(Observer o) {
        super.deleteObserver(o);
        observerList.remove(o);
    }

    public void change() {
        setChanged();
        notifyObservers();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        ObservableImpl that = (ObservableImpl) o;

        return id == that.id;
    }

    @Override
    public String toString() {
        return "ObservableImpl{" +
                "ID=" + id +
                '}';
    }
}

ObserverImpl 

@Entity
public class ObserverImpl implements Observer {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long ID;
    private String name;

    public Long getID() {
        return ID;
    }

    public void setID(Long ID) {
        this.ID = ID;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public ObserverImpl(String name) {
        this.name = name;
    }

    protected ObserverImpl() {
    }


    @Override
    public String toString() {
        return "ObserverImpl{" +
                "ID=" + ID +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        ObserverImpl observer = (ObserverImpl) o;

        return ID == observer.ID;
    }


    @Override
    public void update(Observable o, Object arg) {
        System.out.println(this);
    }
}

错误信息：

2017-06-11 14:40:57.032  INFO 21156 --- [           main] c.e.hibernate.HibernateApplication       : No active profile set, falling back to default profiles: default
2017-06-11 14:40:57.061  INFO 21156 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4516af24: startup date [Sun Jun 11 14:40:57 CEST 2017]; root of context hierarchy
2017-06-11 14:40:57.826  INFO 21156 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration' of type [org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration$$EnhancerBySpringCGLIB$$cfcf04d] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2017-06-11 14:40:58.032  INFO 21156 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-06-11 14:40:58.039  INFO 21156 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2017-06-11 14:40:58.039  INFO 21156 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.14
2017-06-11 14:40:58.091  INFO 21156 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-06-11 14:40:58.091  INFO 21156 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1031 ms
2017-06-11 14:40:58.163  INFO 21156 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2017-06-11 14:40:58.165  INFO 21156 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-06-11 14:40:58.166  INFO 21156 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-06-11 14:40:58.166  INFO 21156 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-06-11 14:40:58.166  INFO 21156 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2017-06-11 14:40:58.387  INFO 21156 --- [           main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'
2017-06-11 14:40:58.394  INFO 21156 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
2017-06-11 14:40:58.428  INFO 21156 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.0.12.Final}
2017-06-11 14:40:58.428  INFO 21156 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2017-06-11 14:40:58.429  INFO 21156 --- [           main] org.hibernate.cfg.Environment            : HHH000021: Bytecode provider name : javassist
2017-06-11 14:40:58.449  INFO 21156 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2017-06-11 14:40:58.501  INFO 21156 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
2017-06-11 14:40:58.596  WARN 21156 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.example.hibernate.obs.ObserverImpl.oservableImpl in com.example.hibernate.obs.ObservableImpl.observerList
2017-06-11 14:40:58.598  INFO 21156 --- [           main] o.apache.catalina.core.StandardService   : Stopping service Tomcat
2017-06-11 14:40:58.606  INFO 21156 --- [           main] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-06-11 14:40:58.612 ERROR 21156 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.example.hibernate.obs.ObserverImpl.oservableImpl in com.example.hibernate.obs.ObservableImpl.observerList
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:856) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
    at com.example.hibernate.HibernateApplication.main(HibernateApplication.java:19) [classes/:na]
Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.example.hibernate.obs.ObserverImpl.oservableImpl in com.example.hibernate.obs.ObservableImpl.observerList
    at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:769) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:719) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:54) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1655) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1623) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:278) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:847) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:874) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:353) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:370) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:359) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    ... 16 common frames omitted


Process finished with exit code 1

非常感谢。

HibernateApplication 

@SpringBootApplication
public class HibernateApplication {


    private static final Logger log = LoggerFactory.getLogger(HibernateApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(HibernateApplication.class);
    }


    @Bean
    public CommandLineRunner addObservables(ObserveableRepository repository) {
        return (args) -> {
            useObserver(repository);

            // fetch all customers
            log.info("Observables found with findAll():");
            log.info("-------------------------------");
            for (ObservableImpl observable : repository.findAll()) {
                log.info(observable.toString());
                observable.change();
            }
            log.info("");

        };
    }

    private void useObserver(ObserveableRepository repository) {
        ObservableImpl observable = new ObservableImpl("1");
        observable.addObserver(new ObserverImpl("firstObserver"));
        observable.addObserver(new ObserverImpl("secondObserver"));
        observable.addObserver(new ObserverImpl("thirdObserver"));
        repository.save(observable);
    }
}

ObserveableRepository 

public interface ObserveableRepository extends CrudRepository<ObservableImpl, Long> {

}

application.properties

spring.datasource.url=jdbc:h2:file:~/test3;DB_CLOSE_ON_EXIT=FALSE;AUTO_RECONNECT=TRUE
spring.datasource.username=admin
spring.datasource.password=password
spring.datasource.driver-class-name=org.h2.Driver
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.H2Dialect

【问题讨论】：

    标签： java hibernate spring-boot spring-data-jpa


    【解决方案1】：

    我建议您重命名您的实体并给它们“简单”和易于理解的名称。这将使您不必关心其字段的复杂定义和可能的错误。

    例如：

    @Entity
public class Experiment extends Observable {
    //...

    @OneToMany(mappedBy = "experiment")
    private Set<Experimenter> experimenters = new HashSet<>();

    //...
} 

@Entity
public class Experimenter extends Observer {
    //...

    @ManyToOne
    private Experiment experiment;

    //...
}

    所以我们在这里有一个经典的双向 OneToMany association

    要从 IDE 访问 H2 数据库，您可以使用 this 答案。

    【讨论】：

      【解决方案2】：

      将ObservableImpl 字段添加到子实体ObserverImpl，如错误消息所示

      @ManyToOne
@JoinColumn(name = "OBSERVABLE_ID")
private ObservableImpl observableImpl;

      【讨论】：

      • 感谢您的贡献。这就是全部？只是私有的 ObservableImpl observableImpl;使用 getter 和 setter 并且在任何地方都没有进一步的注释？如果是这样：它仍然无法正常工作 -> 相同的错误
      • 应该是这样。 ObservableImpl id 的外键现在是否存在于 ObserverImpl 表中？
      • 我认为，您还应该为该字段添加@ManyToOne 注释。
      • 是的，但是mappedBy 元素使这种关系是双向的。
      • tbh 我不知道如何访问 h2 文件数据库并在我的 IDE“进程以退出代码 1 完成”时检查表中是否存在外键。如果我在我的电脑上打开 test3.mv 文件，里面只有不可读的上下文。对不起:( p.s. @ManyToOne 也没有改变任何东西。仍然是同样的错误
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