无法在许多关系JPA中插入Post Mapping json

分类：编程问答

如何解决无法在许多关系JPA中插入Post Mapping json

这是我的第一篇博文，但徒劳地搜索了整个互联网。我是jpa spring休息和学习东西的新手。我的问题如下： 我有3个实体，用户，角色和预订都是双向连接的

用户和角色->许多连接表（user_roles）

用户和图书->许多连接表（book_users）

用户

  @Entity
    @Table(name="users")
    public class User {
    
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="u_id")
    private int id;
    
    @Column(name="username")
    private String username;
    
    @Column(name="password")
    private String password;
    
    //@JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY,cascade = {CascadeType.DETACH,CascadeType.MERGE,CascadeType.PERSIST,CascadeType.REFRESH})
    @JoinTable(name = "book_user",joinColumns = @JoinColumn(name="user_id"),inverseJoinColumns = @JoinColumn(name="book_id"))
    private List<Book> books;
    
    @JsonIgnore
    @OneToMany(fetch = FetchType.EAGER,cascade = CascadeType.ALL)
    @JoinTable(name = "user_role",inverseJoinColumns = @JoinColumn(name="role_id"))
    private Set<Role> roles;
    
    public User() {
        
    }

    public User(String username,String password) {
        super();
        this.username = username;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
    

    public List<Book> getBooks() {
        return books;
    }

    public void setBooks(List<Book> books) {
        this.books = books;
    }
    

    public Set<Role> getRoles() {
        return roles;
    }

    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }
    
    //add a convenience method
        public void addBook(Book theBook) {
            if(books==null) {
                books=new ArrayList<>();
            }
            books.add(theBook);
            
        }

    @Override
    public String toString() {
        return "User [id=" + id + ",username=" + username + ",password=" + password + "]";
    }

    }

书

  @Entity
    @Table(name="books")
    public class Book {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "b_id")
    private int id;
    
    @Column(name="b_name")
    private String bName;
    
    @Column(name = "author")
    private String author;
    
    /*@ManyToMany(fetch = FetchType.LAZY,joinColumns = @JoinColumn(name="book_id"),inverseJoinColumns = @JoinColumn(name="user_id"))
    private List<User> users;*/
    @JsonIgnore
    @ManyToMany(mappedBy = "books",fetch = FetchType.LAZY,CascadeType.REFRESH})
    private List<User> users;
    
    public Book() {
        
    }

    public Book(String name,String author) {
        super();
        this.bName = name;
        this.author = author;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return bName;
    }

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

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
    
    

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }
    
    //add a convenience method
    public void addUser(User theUser) {
        if(users==null) {
            users=new ArrayList<>();
        }
        users.add(theUser);
        
    }
    
    

    @Override
    public String toString() {
        return "Book [id=" + id + ",name=" + bName + ",author=" + author + "]";
    }
    
    

}

角色

    @Entity
    @Table(name = "roles")
    public class Role {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "r_id")
    private int id;
    @Column(name = "r_name")
    private String role;
    
    public Role() {
        
    }

    public Role(String role) {
        super();
        this.role = role;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    @Override
    public String toString() {
        return "Role [id=" + id + ",role=" + role + "]";
    }
    
}

我有3个（用户，书，角色）存储库，它们扩展了JpaRepository。

AdminController 

@RestController
@RequestMapping("/rest")
public class AdminController {
    
    @Autowired
    private BookRepository bookRepository;
    
    @Autowired
    private UserRepository userRepository;
    
    @Autowired
    private RoleRepository roleRepository;
    
    
    
    
    //test purpose
    @GetMapping("/books")
    public List<Book> getBooks(){
        return bookRepository.findAll();
    }
    //add mapping for GET /books/{userId}
    @GetMapping("/books/{userId}")
    public List<Book> getBooksByUserId(@PathVariable int userId) {
        User theUser=userRepository.getOne(userId);
        if(theUser==null) {
            throw new RuntimeException("User Not Found: "+userId);
        }
        List<Book> theBooks=theUser.getBooks();
        if(theBooks==null) {
            throw new RuntimeException("No Books found for the User: "+userId);
        }

        return theBooks;
    }
    
    @PostMapping("/books")
    public Book addBook(@RequestBody Book theBook) {
        
        
        Optional<User> optionalUser=userRepository.findById(1);
        User theAdmin=optionalUser.get();
        System.out.println(theAdmin.getUsername()+" "+theAdmin.getPassword());
        theBook.addUser(theAdmin);
        //theAdmin.addBook(theBook);
        return bookRepository.save(theBook);
        
    }
    
    
    
    //test purpose
    @GetMapping("/users") //every table is connected so we get everything from userRepository
    public List<User> getEverything(){
        return userRepository.findAll();
    }
    
    //test purpose
    @GetMapping("/userBooks")
    public List<UserBookResponse> getBooksByUser(){
        return bookRepository.getBooksByUser();
    }

}

我的要求是只有管理员才能添加，更新，删除为什么我将用户带到id = 1的书（我在数据库中预先将id = 1行指定为admin） 在adminContrller中，PostMapping addBook在我仅以书属性（即b_name和author）发送json时不起作用。显然是因为书是与用户双向连接的。 如果我发送带有嵌套属性的json。仍然遇到同样的问题。 java.sql.SQLIntegrityConstraintViolationException：列“ b_name”不能为null 我了解问题所在，但是解决方法是什么？

错误

{
    "timestamp": "2020-08-23T18:45:26.679+00:00","status": 500,"error": "Internal Server Error","trace": "org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement\r\n\tat org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:298)\r\n\tat org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:255)\r\n\tat org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:528)\r\n\tat org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)\r\n\tat org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)\r\n\tat org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)\r\n\tat com.sun.proxy.$Proxy107.save(Unknown Source)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)\r\n\tat java.lang.reflect.Method.invoke(Unknown Source)\r\n\tat org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)\r\n\tat org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205)\r\n\tat com.sun.proxy.$Proxy70.save(Unknown Source)\r\n\tat com.kk.booklendingapi.booklending1.controller.AdminController.addBook(AdminController.java:84)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)\r\n\tat java.lang.reflect.Method.invoke(Unknown Source)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)\r\n\tat org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)\r\n\tat org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)\r\n\tat org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:652)\r\n\tat org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:733)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320)\r\n\tat org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92)\r\n\tat org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)\r\n\tat org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215)\r\n\tat org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178)\r\n\tat org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)\r\n\tat org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)\r\n\tat org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)\r\n\tat org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)\r\n\tat org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)\r\n\tat org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)\r\n\tat org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)\r\n\tat org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)\r\n\tat org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)\r\n\tat org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)\r\n\tat org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)\r\n\tat org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)\r\n\tat org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)\r\n\tat java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)\r\n\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)\r\n\tat org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)\r\n\tat java.lang.Thread.run(Unknown Source)\r\nCaused by: org.hibernate.exception.ConstraintViolationException: could not execute statement\r\n\tat org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:59)\r\n\tat org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)\r\n\tat org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)\r\n\tat org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)\r\n\tat org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:200)\r\n\tat org.hibernate.dialect.identity.GetGeneratedKeysDelegate.executeAndExtract(GetGeneratedKeysDelegate.java:57)\r\n\tat org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:43)\r\n\tat org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3153)\r\n\tat org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3759)\r\n\tat org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:84)\r\n\tat org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:645)\r\n\tat org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:282)\r\n\tat org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:263)\r\n\tat org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:317)\r\n\tat org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:330)\r\n\tat org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287)\r\n\tat org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193)\r\n\tat org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123)\r\n\tat org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185)\r\n\tat org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128)\r\n\tat org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55)\r\n\tat org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102)\r\n\tat org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:721)\r\n\tat org.hibernate.internal.SessionImpl.persist(SessionImpl.java:707)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)\r\n\tat java.lang.reflect.Method.invoke(Unknown Source)\r\n\tat org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366)\r\n\tat com.sun.proxy.$Proxy100.persist(Unknown Source)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)\r\n\tat java.lang.reflect.Method.invoke(Unknown Source)\r\n\tat org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:314)\r\n\tat com.sun.proxy.$Proxy100.persist(Unknown Source)\r\n\tat org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:554)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)\r\n\tat java.lang.reflect.Method.invoke(Unknown Source)\r\n\tat org.springframework.data.repository.core.support.ImplementationInvocationMetadata.invoke(ImplementationInvocationMetadata.java:72)\r\n\tat org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:382)\r\n\tat org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:205)\r\n\tat org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:549)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:155)\r\n\tat org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367)\r\n\tat org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)\r\n\tat org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)\r\n\t... 93 more\r\nCaused by: java.sql.SQLIntegrityConstraintViolationException: Column 'b_name' cannot be null\r\n\tat com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117)\r\n\tat com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)\r\n\tat com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)\r\n\tat com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953)\r\n\tat com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1092)\r\n\tat com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1040)\r\n\tat com.mysql.cj.jdbc.ClientPreparedStatement.executeLargeUpdate(ClientPreparedStatement.java:1347)\r\n\tat com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdate(ClientPreparedStatement.java:1025)\r\n\tat com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61)\r\n\tat com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java)\r\n\tat org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197)\r\n\t... 143 more\r\n","message": "could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement","path": "/rest/books/"
}

我的数据库

DROP DATABASE  IF EXISTS `spring_boot_bl1`;

CREATE DATABASE  IF NOT EXISTS `spring_boot_bl1`;
USE `spring_boot_bl1`;


---
--- Table Structure for table `books`
---

DROP TABLE IF EXISTS `books`;
CREATE TABLE `books` (
  `b_id` int(10) NOT NULL,`b_name` varchar(50) NOT NULL,`author` varchar(50) NOT NULL,PRIMARY KEY (`b_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

---
--- Inserting data for table books
---

INSERT INTO `books` 
VALUES 
(1,'Papa_Python','KK'),(2,'Java_Blasters','Chad Derby'),(3,'ML_Masters','Josh Starmer');

--
-- Table structure for table `users`
--

DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `u_id` int(10) NOT NULL,`username` varchar(50) NOT NULL,`password` varchar(50) NOT NULL,PRIMARY KEY (`u_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Inserting data for table `users`
--

INSERT INTO `users` 
VALUES 
(1,'john','{noop}test123'),'mary','susan','{noop}test123');

---
--- Table Structure for Tables `roles`
---

DROP TABLE IF EXISTS `roles`;
CREATE TABLE `roles` (
  `r_id` int(10) NOT NULL,`r_name` varchar(50) NOT NULL,PRIMARY KEY (`r_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `roles` 
VALUES 
(1,'ADMIN'),'USER');


CREATE TABLE `user_role` (
  `user_id` int(10) NOT NULL,`role_id` int(10) NOT NULL,PRIMARY KEY (`user_id`,`role_id`),KEY `FK_USER_idx` (`user_id`),CONSTRAINT `FK_USER_05` FOREIGN KEY (`user_id`) 
  REFERENCES `users` (`u_id`) 
  ON DELETE NO ACTION ON UPDATE NO ACTION,CONSTRAINT `FK_ROLE` FOREIGN KEY (`role_id`) 
  REFERENCES `roles` (`r_id`) 
  ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `user_role` 
VALUES 
(1,1),2),2);




CREATE TABLE `book_user` (
  `book_id` int(10) NOT NULL,`user_id` int(10) NOT NULL,PRIMARY KEY (`book_id`,`user_id`),KEY `FK_USER_idx_02` (`user_id`),CONSTRAINT `FK_BOOK_05` FOREIGN KEY (`book_id`) 
  REFERENCES `books` (`b_id`) 
  ON DELETE NO ACTION ON UPDATE NO ACTION,CONSTRAINT `FK_USER` FOREIGN KEY (`user_id`) 
  REFERENCES `users` (`u_id`) 
  ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

---
--- Inserting data for table `book_user`
---
INSERT INTO `book_user` 
VALUES 
(1,(1,3),3);

enter image description here

解决方法

根据您的堆栈跟踪：

Caused by: java.sql.SQLIntegrityConstraintViolationException: Column 'b_name' cannot be null

这导致我检查您的 Book 类定义，其中具有以下内容：

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

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "b_id")
private int id;

@Column(name="b_name")
private String bName;

然后检查您的有效载荷：

{ "b_name":"Angular_Avengers","author":"Anwesha das" }

您可能会看到，您正在发送字段“ b_name”，但是您的类字段称为 bName ，这就是为什么当您打算将其插入数据库时​​该值为null的原因。请按以下方式发送有效载荷：

{ "bName":"Angular_Avengers","author":"Anwesha das" }

让我知道结果。

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