id to load is required for loading原因关于ssh中模型驱动

java.lang.IllegalArgumentException: id to load is required for loading

    org.hibernate.event.LoadEvent.(LoadEvent.java:89)
    org.hibernate.event.LoadEvent.(LoadEvent.java:61)
    org.hibernate.impl.SessionImpl.get(SessionImpl.java:994)
    org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
    org.springframework.orm.hibernate3.HibernateTemplate$1.doInHibernate(HibernateTemplate.java:528)
    org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:419)
    org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374)
    org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:522)
    org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:516)
    cn.bdqn.dao.impl.DepartmentDaoImpl.getDepartmentById(DepartmentDaoImpl.java:48)
    cn.bdqn.dao.impl.DepartmentDaoImpl.deleteDepartmentByID(DepartmentDaoImpl.java:27)
    cn.bdqn.service.impl.DepartmentServiceImpl.deleteDepartmentByID(DepartmentServiceImpl.java:31)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:483)
    org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:310)
    org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
    org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    com.sun.proxy.$Proxy4.deleteDepartmentByID(Unknown Source)
    cn.bdqn.action.DepartmentAction.deleteDepartment(DepartmentAction.java:48)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:483)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
    com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
    com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
    org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
    org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475)
    org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
    org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1368)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:745)
    

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  struts.devMode=false

in your WEB-INF/classes/struts.properties file.

首先，这个报错的原因：在使用hibernate时，有时会遇到这个异常：java.lang.IllegalArgumentException: id to load is required for loading，这是因为在使用类似findbyId(id)的查询时，传入的id为null
那么究竟是哪里导致传入的值为null呢？
这里从Struts2中的模型驱动这一方面来分析。
Struts2的模型驱动在实现ModerDriven<>()接口时，必须保证前台界面的属性名称与实体类的属性名称一致。
那么导致空值就可能是1、没有在action类中实现模型驱动接口；
2、前台接收值得属性名称与实体类名称不一致。

public class DepartmentAction extends BaseAction implements ModelDriven<Department>{
    private Department model = new Department();
    
    public Department getModel() {
        return this.model;
    }

    private DepartmentService departmentService;

    public DepartmentService getDepartmentService() {
        return departmentService;
    }

    public void setDepartmentService(DepartmentService departmentService) {
        this.departmentService = departmentService;
    }
    
    public String getAllDepartment(){
        Collection<Department> departmentList = this.departmentService.getAllDepartment();
        //把departmentList放入到值栈中
        //把一个对象存放到map栈中
        ActionContext.getContext().put("departmentList", departmentList);
        return listAction;
    }
    
    public String deleteDepartment(){
        this.departmentService.deleteDepartmentByID(this.getModel().getDid(), DeleteMode.DEL_PRE_RELEASE);
        return action2action;
    }
    
    
}