我们目前正在Spring MVC中增强已存在的 Web应用程序（我只是在学习框架）。我尝试将另一个属性添加到正被推入数据库的对象中（我也添加了相应的列），但我不断收到NullValueInNestedPathException错误。
我已经尝试了Google，建议如下：
1）明确声明新属性的构造函数（尝试过，但没有解决）
2）确保你实例化新对象（试过，没有解决）
3）仔细检查财产的getter / setters（他们没关系，不是错误）
4）创建serialVersionUID（nah！）
5）使用调试功能（我做了，我发现属性是 null）
请帮忙！ T.T以下是代码：
新物业的VO：
public class ShiftAssignmentLookupVO implements Serializable{
...
public ShiftAssignmentLookupVO(){}
public String getShiftAssignmentStringValue(){
return shiftAssignmentStringValue;
}
public void setShiftAssignmentStringValue(String shiftAssignmentStringValue){
this.shiftAssignmentStringValue = shiftAssignmentStringValue;
}
...
}
包含属性的对象的VO：
public class EmployeeCalendarVO implements Serializable {
...
//the new property:
private ShiftAssignmentLookupVO shiftAssignmentVO = new ShiftAssignmentLookupVO();
public void setShiftAssignmentVO(ShiftAssignmentLookupVO shiftAssignmentVO){
this.shiftAssignmentVO = shiftAssignmentVO;
}
public ShiftAssignmentLookupVO getShiftAssignmentVO(){
return shiftAssignmentVO;
}
...
}
这是hibernate映射：
<class name = "EmployeeCalendarVO" table = "EMP_WRK_CDR">
...
<many-to-one name = "shiftAssignmentVO" lazy = "false">
<column name = "ID_ASSIGNMENT" />
</many-to-one>
...
</class>
我尝试访问该属性的jsp：
<spring:bind path = "employeecalendar.empCalList[${ecl.index}].shiftAssignmentVO.shiftAssignmentID">
...
</spring:bind>
最后（哇！）堆栈跟踪：
Aug 8, 2013 10:36:18 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet dtr threw exception
org.springframework.beans.NullValueInNestedPathException: Invalid property 'empCalList[0].shiftAssignmentVO' of bean class [com.safeway.dtr.employee.vo.EmpCalManager]: Value of nested property 'empCalList[0].shiftAssignmentVO' is null
at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:443)
at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:418)
at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:419)
at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:524)
at org.springframework.validation.AbstractPropertyBindingResult.getActualFieldValue(AbstractPropertyBindingResult.java:78)
at org.springframework.validation.AbstractBindingResult.getFieldValue(AbstractBindingResult.java:337)
at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:119)
at org.springframework.web.servlet.tags.BindTag.doStartTagInternal(BindTag.java:116)
at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:77)
at org.apache.jsp.WEB_002dINF.jsp.employee.employeecalendar_jsp._jspService(employeecalendar_jsp.java:1184)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:624)
at org.apache.struts.tiles.TilesUtilImpl.doInclude(TilesUtilImpl.java:135)
at org.apache.struts.tiles.TilesUtil.doInclude(TilesUtil.java:149)
at org.apache.struts.tiles.taglib.InsertTag.doInclude(InsertTag.java:761)
at org.apache.struts.tiles.taglib.InsertTag$InsertHandler.doEndTag(InsertTag.java:893)
at org.apache.struts.tiles.taglib.InsertTag.doEndTag(InsertTag.java:462)
at org.apache.jsp.WEB_002dINF.jsp.defaultLayout_jsp._jspx_meth_tiles_005finsert_005f1(defaultLayout_jsp.java:286)
at org.apache.jsp.WEB_002dINF.jsp.defaultLayout_jsp._jspService(defaultLayout_jsp.java:115)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:145)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:251)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1144)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:880)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:793)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:431)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:595)
Hi drurenia，这是empCalManager的要求：
public class EmpCalManager {
...
private List<EmployeeCalendarVO> empCalList = LazyList.decorate(new ArrayList<EmployeeCalendarVO>(),FactoryUtils.instantiateFactory(EmployeeCalendarVO.class));
public List<EmployeeCalendarVO> getEmpCalList() {
return empCalList;
}
public void setEmpCalList(List<EmployeeCalendarVO> empCalList) {
this.empCalList = empCalList;
}
...
}
这篇文章从表格中拉出来：
public List<EmployeeCalendarVO> getEmployeeWorkCalendar(int empId, Date from, Date to){
Session session = sessionFactory.getCurrentSession();
session.flush();
Query query = session.createQuery(" from EmployeeCalendarVO as empWrkCdr where " +
"empWrkCdr.employeeId = ? AND empWrkCdr.workDate between ? AND ? order by empWrkCdr.workDate");
query.setInteger(0, empId);
query.setDate(1, from);
query.setDate(2, to);
return query.list();
}
有什么想法吗？建议？ 感谢任何有帮助的人！
* PS如果本帖中缺少某些代码/部分代码，请通知我，以便我发布。
答案 0 :(得分：0)
我发现了什么问题：似乎我将新属性的列的默认值设置为null！我希望得到同样错误的其他人尝试解决这个问题。 -__-！感谢drurenia感兴趣！ ：d