com.jfinal.plugin.activerecord.ActiveRecordException: You can't update model without Primary Key, id can not be null.

at com.jfinal.plugin.activerecord.Model.update(Model.java:506)

at com.oss.model.StockInformation$$EnhancerByCGLIB$$ac975a7b.CGLIB$update$24()

at com.oss.model.StockInformation$$EnhancerByCGLIB$$ac975a7b$$FastClassByCGLIB$$8540dc36.invoke()

at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)

at com.jfinal.aop.Invocation.invoke(Invocation.java:82)

at com.jfinal.aop.Callback.intercept(Callback.java:96)

at com.oss.model.StockInformation$$EnhancerByCGLIB$$ac975a7b.update()

at intercept.inventoryIntercept.addBefore(inventoryIntercept.java:36)

at com.eova.widget.form.FormController$1.run(FormController.java:95)

at com.jfinal.plugin.activerecord.DbPro.tx(DbPro.java:720)

at com.jfinal.plugin.activerecord.DbPro.tx(DbPro.java:757)

at com.jfinal.plugin.activerecord.Db.tx(Db.java:460)

at com.eova.widget.form.FormController.doAdd(FormController.java:86)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.lang.reflect.Method.invoke(Unknown Source)

at com.jfinal.aop.Invocation.invoke(Invocation.java:73)

at com.eova.interceptor.LoginInterceptor.intercept(LoginInterceptor.java:50)

at com.jfinal.aop.Invocation.invoke(Invocation.java:67)

at com.jfinal.core.ActionHandler.handle(ActionHandler.java:74)

at com.jfinal.plugin.druid.DruidStatViewHandler.handle(DruidStatViewHandler.java:75)

at com.jfinal.core.JFinalFilter.doFilter(JFinalFilter.java:72)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)

at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)

at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)

at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

at java.lang.Thread.run(Unknown Source)

这是项目报的错，请问该如何解决啊！问题已解决