我有两个JPA实体User和Authority，User的父级和Authority是子级。用户和授权之间存在一对多的关系。

用户-

@Data
@Entity
@Table(name = "users", uniqueConstraints={ @UniqueConstraint(columnNames={"username"})})
public class User {

    @Id
    @CustomEmailValidator
    @Size.List ({
            @Size(min=5, message="The field must be at least {min} characters"),
            @Size(max=100, message="The field must be less than {max} characters")
    })
    private String username;

    @Basic
    @Column(name = "enabled", columnDefinition = "BIT", length = 1)
    private boolean enabled;

    @OneToMany(cascade = {CascadeType.ALL,CascadeType.PERSIST,CascadeType.MERGE}, mappedBy = "user")
    @Column(nullable = false)
    private List<Authority> authorities = new ArrayList<>();
}

权限-

@Data
@Entity
@Table(name ="authorities")
public class Authority {

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

    @Version
    private Integer version;

    @NotNull
    @Size.List ({
            @Size(min=5, message="The field must be at least {min} characters"),
            @Size(max=100, message="The field must be less than {max} characters")
    })
    private String authority;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "username", nullable=false)
    private User user;
}

我已经将User公开为Spring Data Rest存储库。当我执行 http：// localhost / api /
users时， 我可以看到用于列出权限的用途。但是，当我尝试使用以下json与权限一起创建用户时-

{
   "username": "cmsdeveloper222@amnesty.org.in",
   "enabled": true,
   "authorities": [
    {

       "authority": "ROLE_ADMIN"
    }
    ]

}

我收到以下错误-

{
    "cause": {
        "cause": {
            "cause": null,
            "message": "Column 'username' cannot be null"
        },
        "message": "could not execute statement"
    },
    "message": "could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement"
}

潜在的例外是-

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'username' cannot be null
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_40]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_40]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_40]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422) ~[na:1.8.0_40]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:377) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.Util.getInstance(Util.java:360) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:971) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3887) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3823) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2435) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2582) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2530) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1907) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2141) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2077) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2062) ~[mysql-connector-java-5.1.34.jar:5.1.34]
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    ... 151 common frames omitted
Hibernate: select count(campaign0_.id) as col_0_0_ from Campaign campaign0_
Hibernate: select campaign0_.id as id1_0_, campaign0_.campaignId as campaign2_0_, campaign0_.emailOfTheCreator as emailOfT3_0_, campaign0_.endDate as endDate4_0_, campaign0_.name as name5_0_, campaign0_.startDate as startDat6_0_, campaign0_.status as status7_0_, campaign0_.summary as summary8_0_, campaign0_.version as version9_0_ from Campaign campaign0_ limit ?
Hibernate: select user0_.username as username1_3_1_, user0_.enabled as enabled2_3_1_, authoritie1_.username as username4_3_3_, authoritie1_.id as id1_2_3_, authoritie1_.id as id1_2_0_, authoritie1_.authority as authorit2_2_0_, authoritie1_.username as username4_2_0_, authoritie1_.version as version3_2_0_ from users user0_ left outer join authorities authoritie1_ on user0_.username=authoritie1_.username where user0_.username=?
Hibernate: insert into users (enabled, username) values (?, ?)
Hibernate: insert into authorities (authority, username, version) values (?, ?, ?)
16:48:14.260 [http-nio-8080-exec-1] WARN  o.h.e.jdbc.spi.SqlExceptionHelper - SQL Error: 1048, SQLState: 23000
16:48:14.267 [http-nio-8080-exec-1] ERROR o.h.e.jdbc.spi.SqlExceptionHelper - Column 'username' cannot be null
16:48:14.271 [http-nio-8080-exec-1] WARN  o.h.e.jdbc.spi.SqlExceptionHelper - SQL Warning Code: 1048, SQLState: 23000
16:48:14.271 [http-nio-8080-exec-1] WARN  o.h.e.jdbc.spi.SqlExceptionHelper - Column 'username' cannot be null
16:48:14.308 [http-nio-8080-exec-1] ERROR o.s.d.r.w.AbstractRepositoryRestController - could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:248) ~[spring-orm-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:214) ~[spring-orm-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:417) ~[spring-orm-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59) ~[spring-tx-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213) ~[spring-tx-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147) ~[spring-tx-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodIntercceptor.invoke(CrudMethodMetadataPostProcessor.java:122) ~[spring-data-jpa-1.7.2.RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at com.sun.proxy.$Proxy98.save(Unknown Source) ~[na:na]
    at org.springframework.data.rest.core.invoke.CrudRepositoryInvoker.invokeSave(CrudRepositoryInvoker.java:106) ~[spring-data-rest-core-2.2.2.RELEASE.jar:na]
    at org.springframework.data.rest.webmvc.RepositoryEntityController.createAndReturn(RepositoryEntityController.java:414) ~[spring-data-rest-webmvc-2.2.2.RELEASE.jar:na]
    at org.springframework.data.rest.webmvc.RepositoryEntityController.postCollectionResource(RepositoryEntityController.java:232) ~[spring-data-rest-webmvc-2.2.2.RELEASE.jar:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_40]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_40]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_40]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_40]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) ~[spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) [spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868) [spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:644) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) [spring-webmvc-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationProcessingFilter.doFilter(OAuth2AuthenticationProcessingFilter.java:140) [spring-security-oauth2-2.0.2.RELEASE.jar:na]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) [spring-security-web-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_40]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_40]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.20.jar:8.0.20]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_40]
Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:72) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:211) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3558) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:98) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:492) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:197) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:181) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:216) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:324) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:288) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.jpa.event.internal.core.JpaMergeEventListener.saveWithGeneratedId(JpaMergeEventListener.java:73) ~[hibernate-entitymanager-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:271) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:251) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:189) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:886) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:868) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.spi.CascadingActions$6.cascade(CascadingActions.java:277) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:350) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:293) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:379) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:319) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:296) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:460) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:255) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:317) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:186) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:85) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:876) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:858) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:863) ~[hibernate-core-4.3.8.Final.jar:4.3.8.Final]
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1196) ~[hibernate-entitymanager-4.3.8.Final.jar:4.3.8.Final]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_40]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_40]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_40]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_40]
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:344) ~[spring-orm-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at com.sun.proxy.$Proxy93.merge(Unknown Source) ~[na:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_40]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_40]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_40]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_40]
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:291) ~[spring-orm-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at com.sun.proxy.$Proxy93.merge(Unknown Source) ~[na:na]
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:410) ~[spring-data-jpa-1.7.2.RELEASE.jar:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_40]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_40]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_40]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_40]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:416) ~[spring-data-commons-1.9.2.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:401) ~[spring-data-commons-1.9.2.RELEASE.jar:na]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:373) ~[spring-data-commons-1.9.2.RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$DefaultMethodInvokingMethodInterceptor.invoke(RepositoryFactorySupport.java:486) ~[spring-data-commons-1.9.2.RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.5.RELEASE.jar:4.1.5.RELEASE]

请帮忙。我做错了什么？为什么在进行映射时，hibernate抱怨用户名为null？我的json是否可能未正确转换？

谢谢，维杰