spring-boot - 使用带有 MySQL 数据库的 Spring Boot Rest API 的一对一映射
问题描述
我正在尝试在 spring Boot Rest Api 中创建一个嵌套自定义类型。我创建了 Book.java 实体类
package com.api.book.bootrestbook.entities;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;
@Entity
@Table(name = "Book")
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "Book_ID")
private int id;
private String title;
@OneToOne(cascade = CascadeType.ALL)
private Author author;
}
作者.java
package com.api.book.bootrestbook.entities;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "Author")
public class Author {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int authorId;
@Column(name = "first_name")
private String firstName;
private String lastName;
private String language;
}
我正在尝试将 Book 类作者数据成员与 Author 类对象映射。
这是我的处理程序方法，它将用于填充数据库表中请求的详细信息。
@PostMapping("/books")
public Book addBook(@RequestBody Book book) {
this.bookServiceJPA.addBook(book);
return book;
}
这是我的 BookServiceJPA 课程 -
package com.api.book.bootrestbook.services;
import java.util.List;
import javax.sound.sampled.Line;
import com.api.book.bootrestbook.dao.BookRepository;
import com.api.book.bootrestbook.entities.Book;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class BookServiceJPA {
@Autowired
private BookRepository bookRepository;
// adding a book for post request, We have to use post method for this purpose
public void addBook(Book b) {
this.bookRepository.save(b);
System.out.println("Book details saved");
return;
}
}
这是我的 BookRepository 界面 -
import org.springframework.data.repository.CrudRepository;
public interface BookRepository extends CrudRepository<Book, Integer>{
public Book findById(int id);
}
运行我的应用程序后，它正在运行并且表也被创建但是当我试图发出请求时
我的代码在控制台中显示此错误 -
2021-04-13 00:16:47.581 INFO 9404 --- [nio-8080-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-04-13 00:16:47.583 INFO 9404 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-04-13 00:16:47.591 INFO 9404 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet : Completed initialization in 4 ms
2021-04-13 00:16:48.032 ERROR 9404 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessApiUsageException: detached entity passed to persist: com.api.book.bootrestbook.entities.Author; nested exception is org.hibernate.PersistentObjectException: detached entity passed to persist: com.api.book.bootrestbook.entities.Author] with root cause
org.hibernate.PersistentObjectException: detached entity passed to persist: com.api.book.bootrestbook.entities.Author
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:120) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:104) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:492) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:416) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:218) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:151) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:93) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:720) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:706) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[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.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.5.jar:5.3.5]
at com.sun.proxy.$Proxy83.persist(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311) ~[spring-orm-5.3.5.jar:5.3.5]
at com.sun.proxy.$Proxy83.persist(Unknown Source) ~[na:na]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:557) ~[spring-data-jpa-2.4.6.jar:2.4.6]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.data.repository.core.support.RepositoryMethodInvoker$RepositoryFragmentMethodInvoker.lambda$new$0(RepositoryMethodInvoker.java:289) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:524) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:285) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:531) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:156) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:131) ~[spring-data-commons-2.4.6.jar:2.4.6]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) ~[spring-tx-5.3.5.jar:5.3.5]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) ~[spring-tx-5.3.5.jar:5.3.5]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.5.jar:5.3.5]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.5.jar:5.3.5]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174) ~[spring-data-jpa-2.4.6.jar:2.4.6]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.5.jar:5.3.5]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.5.jar:5.3.5]
at com.sun.proxy.$Proxy86.save(Unknown Source) ~[na:na]
at com.api.book.bootrestbook.services.BookServiceJPA.addBook(BookServiceJPA.java:26) ~[classes/:na]
at com.api.book.bootrestbook.controllers.BookController.addBook(BookController.java:80) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[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.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.5.jar:5.3.5]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.3.5.jar:5.3.5]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652) ~[tomcat-embed-core-9.0.44.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.5.jar:5.3.5]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.44.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.5.jar:5.3.5]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.5.jar:5.3.5]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.5.jar:5.3.5]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.5.jar:5.3.5]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1707) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.44.jar:9.0.44]
at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]
我不知道为什么它显示错误。我已经复制了视频中的所有步骤。他的应用程序正在运行，但我的应用程序显示错误。有人请帮助我。
解决方案
我认为将一对一映射设置为双向是一个很好的做法。在您当前的设置中，它是单向的，其中 Book 是拥有/父实体。应该是作者吗？
如果我们将重构您的代码，它应该看起来与此类似（未经测试）。
注意：这假设作者存在。否则，我们将使用AuthorController, AuthorService, AuthorRepository.
作者实体.java *
@Entity
@Table(name = "Author")
public class Author {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int authorId;
@Column(name = "first_name")
private String firstName;
@Column(name = “last_name")
private String lastName;
@Column(name = “language”)
private String language;
@OneToOne(
mappedBy = “book”,
orphanRemoval = true,
cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE },
fetch = FetchType.EAGER
)
private Book book;
}
BookEntity.java
@Entity
@Table(name = "Book")
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "Book_ID")
private int id;
@Column(name = “title”)
private String title;
@JoinColumn(
name = “author_id",
referencedColumnName = "id",
foreignKey = @ForeignKey(name = “author_book_fk")
)
private Author author;
}
在您的BookController.java中，您必须期待@RequestBody以下内容：title: ‘Data JPA’, author: 1
在您的BookService.java中，您可以执行此操作。
public Book save(String bookTitle, Long authorId) {
Author author = authorService.findById(authorId); // should be formatted to 1L, 2L, etc…
Book book = new Book();
book.setTitle(bookTitle);
book.setAuthor(author);
bookRepository.save(book);
}
*我建议你使用 DTO 来处理控制器<->服务之间的数据。
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