分離的實體傳遞到彈簧數據持久異常

我正在創建一個應用程序，我需要執行一個實體書的CRUD操作。我正在使用spring數據來執行CURD操作。本書實體引用了兩個名爲Author和Publisher的外部實體。現在，當我點擊保存方法上Book實體是給了我下面的異常分離的實體傳遞到彈簧數據持久異常

org.hibernate.PersistentObjectException: detached entity passed to persist: com.shreyas.finder.domain.person.Author 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:765) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:758) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener$1.cascade(JpaPersistEventListener.java:80) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:398) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:162) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:111) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:425) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:249) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:178) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:109) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:775) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:748) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:753) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1146) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121] 
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121] 
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:347) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at com.sun.proxy.$Proxy78.persist(Unknown Source) ~[na:na] 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121] 
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121] 
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:298) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at com.sun.proxy.$Proxy78.persist(Unknown Source) ~[na:na] 
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:508) ~[spring-data-jpa-1.11.3.RELEASE.jar:na] 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121] 
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121] 
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:504) ~[spring-data-commons-1.13.3.RELEASE.jar:na] 
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:489) ~[spring-data-commons-1.13.3.RELEASE.jar:na] 
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461) ~[spring-data-commons-1.13.3.RELEASE.jar:na] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:61) ~[spring-data-commons-1.13.3.RELEASE.jar:na] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) ~[spring-tx-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282) ~[spring-tx-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136) ~[spring-tx-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133) ~[spring-data-jpa-1.11.3.RELEASE.jar:na] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57) ~[spring-data-commons-1.13.3.RELEASE.jar:na] 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213) ~[spring-aop-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at com.sun.proxy.$Proxy85.save(Unknown Source) ~[na:na] 
at com.shreyas.finder.service.book.BookServiceImpl.save(BookServiceImpl.java:103) ~[classes/:na] 
at com.shreyas.finder.web.book.BookController.save(BookController.java:82) ~[classes/:na] 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121] 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121] 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121] 
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121] 
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE] 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_121] 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_121] 
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.14.jar:8.5.14] 
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_121]

這裏是我的代碼：

Book.java

@Entity 
@Table(name = "book") 
public class Book { 

    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    private long id; 

    @Column(name = "book_title", nullable = false) 
    private String bookTitle; 

    @Column(name = "book_description", nullable = true) 
    private String bookDescription; 

    @Column(name = "book_unit_price", nullable = false) 
    private Float bookUnitPrice; 

    @OneToOne(cascade = CascadeType.ALL) 
    @JoinColumn(name = "author_id") 
    private Author author; 

    @OneToOne(cascade = CascadeType.ALL) 
    @JoinColumn(name = "publisher_id") 
    private Publisher publisher; 
}

BookDAO.java

@Repository("bookDao") 
public interface BookDAO extends JpaRepository<Book, Long> { 

    public List<Book> findByBookTitle(String name); 

    public List<Book> findByBookUnitPrice(Float price); 

    public List<Book> findByBookUnitPriceBetween(Float start , Float end); 
}

BookServiceImpl.java具有以下執行保存方法

@Override 
public Book save(Book book) { 
    if(!bookDao.exists(book.getId())) 
    return bookDao.save(book); 
    else { 
    Book existingBook = bookDao.findOne(book.getId()); 
    existingBook.setBookTitle(book.getBookTitle()); 
    existingBook.setBookDescription(book.getBookDescription()); 
    existingBook.setAuthor(book.getAuthor()); 
    existingBook.setPublisher(book.getPublisher()); 
    return bookDao.save(existingBook); 
    } 
}

BookController.java具有以下保存休息端點的實現。

@RequestMapping(value = "/save", method = RequestMethod.POST, consumes = "application/json", 
    produces = "application/json") 
public ResponseEntity<Book> save(@RequestBody Book book) { 
    return new ResponseEntity<Book>(bookService.save(book), HttpStatus.OK); 
}

並finnaly我傳遞給保存方法的有效載荷。

{ 
    "bookTitle": "Java Complete Reference", 
    "bookDescription": "A great book to start java for beginners", 
    "bookUnitPrice": 100, 
    "author": { 
    "id": 1, 
    "firstName": "First Name", 
    "lastName": "Last Name", 
    "bio": "Author Bio" 
    }, 
    "publisher": { 
    "id": 4, 
    "publisherName": "Continental Publications" 
    } 
}

當我通過HTTP post方法將此有效載荷傳遞給其餘端點時，我得到上述異常。現在我想要堅持一個Book實體，它指向現有的Author和Publisher實體。我搜索了一些類似的問題，但沒有一個解決方案是我的幫助。可以有人請建議我做錯了什麼，需要改變什麼？

感謝您的幫助提前。

來源

2017-06-09 Shreyas Nargund

我想提的另一件事是，這個實體的其他操作做工精細的問題是與創建和更新operations.I我得到正確的結果get方法 –

請點擊這裏... https：//開頭計算器.com/q/13370221/7504001 –

@VikasSuryawanshi感謝您的快速回復。我只是想確保我以正確的格式傳遞有效載荷？ –

我正在通過這個question在stackoverflow和嘗試其解決方案之一，它爲我工作。與

@OneToOne(cascade = CascadeType.MERGE)

更換

@OneToOne(cascade = CascadeType.ALL)

爲我工作。現在我不知道它是否是熱修復或爲什麼我沒有使用CascadeType.ALL

來源

2017-06-09 09:17:45

你正在傳遞'book.getAuthor（）'和'book.getPublisher（）'兩者在更新的情況下分離，所以這就是爲什麼你會得到異常。您還應該從數據庫中檢索它們並更新字段。 –

這是一個一般的架構問題，我很少看到這個問題。

的一點是，你的JPA實體可以在幾種狀態：

瞬態只有
持久不變附
持久不變的分離
持續改變超脫
持續改附着未刷新
持續改附刷新

我經常看到JPA實體通過周圍甚至系列化，使他們退出JPA上下文中成爲「分離」。

你應該在建築文脈明確回答您的JPA實體的任何狀態。如果你不適應它，它就變成了微觀管理，你的代碼將變得越來越無法表達，因爲你總是需要知道哪種方法可以省去調用JPA實體的哪個狀態。

你的問題：

一個簡單的可能性是通過ID加載實體獲得一個附加的表示和值從分離的實體映射到連接實體。

真正的問題是，你的實體悄然成爲通信對象（我稱之爲的建議或提案的對象）。它是在執行（創建/更新/刪除/讀取）操作的上下文中一起工作的對象。這就是說它只是建築冰山的一角。

來源

2017-06-09 09:24:12 oopexpert

分離的實體傳遞到彈簧數據持久異常

回答

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