java - 无法保存 spring JPA 与数据库 : Could not set field value by reflection: [. ..] 的多对多关系，根本原因是 java.lang.NullPointerException

Question

这个问题已经有答案了:

Hibernate complains for null @Id in @OneToOne even if it is not null (1 个回答)

已关闭 3 年前。

我正在尝试在 Spring JPA 中创建一个多对多关系的对象并将其保存到数据库中。当尝试做ReservationRepository.save(res)时我会收到以下错误

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: Could not set field value [1] value by reflection : [class com.example.student.entities.ReservationKey.groupId] setter of com.example.student.entities.ReservationKey.groupId; nested exception is org.hibernate.PropertyAccessException: Could not set field value [1] value by reflection : [class com.example.student.entities.ReservationKey.groupId] setter of com.example.student.entities.ReservationKey.groupId] with root cause java.lang.NullPointerException

这是我想要完成的任务的图表: Database diagram

这似乎与 ReservationKey 中的 groupId setter 有关。但我找不到它似乎有什么问题。我还尝试在 int 和 Integer 之间切换，但这没有帮助。

群组实体

@Entity
@Table(name = "user_group")
public class Group {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true)
    private Integer id;


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


    @OneToMany(mappedBy = "group")
    Set<Reservation> reservations;

    // constructors, getters, setters and stuff

用户实体

@Entity
public class User implements UserDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) // same as SQL autoincrement
    @Column(name = "id", nullable = false)
    private Integer id;

    @Column(name = "emailAddress", unique = true, nullable = false)
    private String emailAddress;

    @Column(name = "password", nullable = false, length = 60)
    private String password;

    @Column(name = "enabled")
    private boolean accountIsEnabled = true;

    @OneToMany(mappedBy = "user")
    Set<Reservation> reservations;

    // constructors, getters, setters and stuff

预订实体

@Entity
public class Reservation {

    @EmbeddedId
    ReservationKey reservationKey;

    @ManyToOne
    @MapsId("userId")
    @JoinColumn(name = "user_id")
    private User user;

    @ManyToOne
    @MapsId("groupId")
    @JoinColumn(name = "group_id")
    private Group group;

    @MapsId("myDate")
    @JoinColumn(name = "my_date")
    @Temporal(TemporalType.DATE)
    private Date date;

    @Column(name = "amount_cooking")
    private int amountCooking;

    @Column(name = "amount_eating")
    private int amountEating;

    public Reservation() {

    }

    public Reservation(User user, Group group, Date my_date, int amountCooking, int amountEating) {
        this.user = user;
        this.group = group;
        this.amountCooking = amountCooking;
        this.amountEating = amountEating;
    }

    // getters, setters and stuff

预订复合键

@Embeddable
public class ReservationKey implements Serializable {

    @Column(name = "my_date")
    @Temporal(TemporalType.DATE)
    private Date myDate;

    @Column(name = "group_id")
    private int groupId;

    @Column(name = "user_id")
    private int userId;

    public ReservationKey() {

    }

    public ReservationKey(Date myDate, int groupId, int userId) {
        this.myDate = myDate;
        this.groupId = groupId;
        this.userId = userId;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof ReservationKey)) return false;
        ReservationKey that = (ReservationKey) o;
        return groupId == that.groupId &&
                userId == that.userId &&
                Objects.equals(myDate, that.myDate);
    }

    @Override
    public int hashCode() {
        return Objects.hash(myDate, groupId, userId);
    }

    public Date getMyDate() {
        return myDate;
    }

    public void setMyDate(Date date) {
        this.myDate = date;
    }

    public int getGroupId() {
        return groupId;
    }

    public void setGroupId(int groupId) {
        this.groupId = groupId;
    }

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }
}

完整的堆栈跟踪

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: Could not set field value [1] value by reflection : [class com.example.student.entities.ReservationKey.groupId] setter of com.example.student.entities.ReservationKey.groupId; nested exception is org.hibernate.PropertyAccessException: Could not set field value [1] value by reflection : [class com.example.student.entities.ReservationKey.groupId] setter of com.example.student.entities.ReservationKey.groupId] with root cause
java.lang.NullPointerException: null
at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:57) ~[na:na]
at java.base/jdk.internal.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:75) ~[na:na]
at java.base/java.lang.reflect.Field.set(Field.java:780) ~[na:na]
at org.hibernate.property.access.spi.SetterFieldImpl.set(SetterFieldImpl.java:41) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.mapping.Component$ValueGenerationPlan.execute(Component.java:498) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.id.CompositeNestedGeneratedValueGenerator.generate(CompositeNestedGeneratedValueGenerator.java:97) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:115) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:696) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at com.sun.proxy.$Proxy97.persist(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:314) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at com.sun.proxy.$Proxy97.persist(Unknown Source) ~[na:na]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:554) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:371) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:204) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:657) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:621) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:605) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366) ~[spring-tx-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at com.sun.proxy.$Proxy117.save(Unknown Source) ~[na:na]
at com.example.student.controllers.ReservationController.makeReservation(ReservationController.java:67) ~[main/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[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:567) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPut(FrameworkServlet.java:920) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:663) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:155) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:92) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1594) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at java.base/java.lang.Thread.run(Thread.java:830) ~[na:na]

保存新对象

@RestController
public class ReservationController {

    @Autowired
    UserRepository userRepository;

    @Autowired
    GroupRepository groupRepository;

    @Autowired
    ReservationRepository reservationRepository;

    @PutMapping(path = "/reserve", consumes = MediaType.APPLICATION_JSON_VALUE)
    void makeReservation(@RequestBody String json) {

        User user = new User("Wouter", new BCryptPasswordEncoder().encode("123"), true);
        userRepository.save(user);
        Group group = new Group("Group1");
        groupRepository.save(group);
        userRepository.flush();
        groupRepository.flush();

        Group g = groupRepository.findByName("Group1").get();
        User p = userRepository.findUserById(1);

        Date date = new Date(System.currentTimeMillis());
        Reservation res = new Reservation(p, g, date, 0, 1);
        reservationRepository.save(res);
        System.out.println(res);

    }

更新:我通过添加 this.reservationKey = new ReservationKey(my_date, user.getId(), group.getId()); 修复了它到 Reservation 的构造函数。之后我得到了一个不同的错误，通过删除 private Date date 修复了该错误以及与预订相关的所有内容。该日期可以从 reservation.getReservationKey().getDate() 访问.

Answer 1

在组类和用户类上初始化预订，即

设置保留 = new HashSet<>();