java JSF选取列表为空，因此转换错误

Question

我快疯了，因为我不知道我的挑选名单出了什么问题。当我按下提交按钮时，目标列表为空。这当然会产生一个转换错误： {0}：发生转换错误。 我简化了下面发布的代码，但它应该包含所有必要的元素

挑选名单。xhtml

<p:pickList id="pickListQuestions"
                value="#{questionController.surveyQuestionPickList}" var="question"
                itemLabel="#{question.question}" itemValue="#{question}" converter="questionConverter"/>

            <h:commandButton id="questionSubmit" value="Add questions"
                action="#{questionController.addQuestions()}" />

。java

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;

import com.survey.jsfController.ApplicationController;
import com.survey.model.Question;

@FacesConverter("questionConverter")
public class QuestionConverter implements Converter {

    public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
        if (value != null && value.trim().length() > 0) {
            return  ApplicationController.getQuestionService().retrieveById(Long.parseLong(value));
        }
        return null;
    }

    public String getAsString(FacesContext fc, UIComponent uic, Object object) {
        if (object == null || object.equals("")) {
            return "";
        } else {
            return String.valueOf(((Question) object).getId());
        }
    }
}

问题控制器。java

import java.io.Serializable;
import java.rmi.RemoteException;
import java.util.ArrayList;
import java.util.List;

import javax.annotation.PostConstruct;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;

import org.primefaces.model.DualListModel;

import com.survey.model.Answer;
import com.survey.model.Question;
import com.survey.model.QuestionType;
import com.survey.model.Survey;

@RequestScoped //@SessionScoped didn't change anything
@ManagedBean(name = "questionController")
public class QuestionController extends Controller implements Serializable {

    public QuestionController() {
        surveyQuestionPickList = new DualListModel<Question>();
        questionAnswerPickList = new DualListModel<Answer>();
    }

    @PostConstruct
    private void init() {
        setSurvey(getSessionController().getSurvey());
        surveyQuestionPickList.setSource(getQuestions());
        if (getSurvey().getQuestions() != null)
            surveyQuestionPickList.setTarget(getSurvey().getQuestions());
        else {
            List<Question> questionTarget = new ArrayList<Question>();
            surveyQuestionPickList.setTarget(questionTarget);
        }

    }

    private static final long serialVersionUID = 1L;

    private Question question;

    private DualListModel<Question> surveyQuestionPickList;

    private Survey survey;
    private String surveyId;
    @ManagedProperty("#{sessionController}")
    private SessionController sessionController;

    public Question getQuestion() {
        return question;
    }

    public void setQuestion(Question question) {
        this.question = question;
    }

    public SessionController getSessionController() {
        return sessionController;
    }

    public void setSessionController(SessionController sessionController) {
        this.sessionController = sessionController;
    }

    public Survey getSurvey() {
        return survey;
    }

    public void setSurvey(Survey survey) {
        this.survey = survey;
    }

    public List<Question> getQuestions() {
        return ApplicationController.getQuestionService().retrieveAll();
    }

    public void setSurveyQuestionPickList(
            DualListModel<Question> surveyQuestionPickList) {
        this.surveyQuestionPickList = surveyQuestionPickList;
    }

    public DualListModel<Question> getSurveyQuestionPickList() {
        return surveyQuestionPickList;
    }

    public void addQuestions() {
        getSurvey().setQuestions(surveyQuestionPickList.getTarget());
        ApplicationController.getSurveyService().update(getSurvey());
        getSessionController().setSurvey(getSurvey());
    }

}

更新1

我感觉在冬眠阶段出了点问题

刀。java（retrieveById被推广为适用于所有模式类的函数）

public Object retrieveById(Class<?> c, long id) {
    return (Object) getSession().get(c, id);
}

新转换器。java

public class QuestionConverter implements Converter {

public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
    if (value != null && value.trim().length() > 0) {
        PickList p = (PickList) uic;
        DualListModel dl = (DualListModel) p.getValue();
        return dl.getSource().get(Integer.valueOf(value));
    }
    return null;
}

public String getAsString(FacesContext fc, UIComponent uic, Object object) {
    if (object == null || object.equals("")) {
        return "";
    } else {
        PickList  p = (PickList) uic;
        DualListModel dl = (DualListModel) p.getValue();
        return  String.valueOf(dl.getSource().indexOf(object));
    }
}
}

调查。java（model）与问题的关系是单向的。只有Survey会存储链接，因为问题可以属于多个Survey

@Entity
@Table(name = "surveys")
public class Survey {

@Id @GeneratedValue
@Column(name = "id")
private long id;

@Column(name = "surveyName")
String surveyName;

@Column(name = "surveyDescription")
String surveyDescription;

@Column(name = "creationCalendar")
Calendar creationCalendar;

@Column(name = "updateCalendar")
Calendar updateCalendar;

@OneToMany//(fetch=FetchType.EAGER)
@Cascade(CascadeType.ALL)
List<Question> questions;

最后但并非最不重要的是，我最近的错误消息：

javax.faces.el.EvaluationException: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.survey.model.Question.id
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:724)
Caused by: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.survey.model.Question.id
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:60)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:346)
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4746)
at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4465)
at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:243)
at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:100)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:684)
at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:676)
at org.hibernate.engine.spi.CascadingActions$5.cascade(CascadingActions.java:235)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:350)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:293)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:379)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:319)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:296)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:86)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.cascadeOnUpdate(DefaultSaveOrUpdateEventListener.java:375)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:349)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:244)
at org.hibernate.event.internal.DefaultUpdateEventListener.performSaveOrUpdate(DefaultUpdateEventListener.java:55)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireUpdate(SessionImpl.java:739)
at org.hibernate.internal.SessionImpl.update(SessionImpl.java:731)
at org.hibernate.internal.SessionImpl.update(SessionImpl.java:726)
at com.survey.daoImplementation.ObjectDaoImplementation.update(ObjectDaoImplementation.java:76)
at com.survey.serviceImplementation.SurveyServiceImplementation.update(SurveyServiceImplementation.java:47)
at com.survey.jsfController.QuestionController.addQuestions(QuestionController.java:200)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at javax.el.ELUtil.invokeMethod(ELUtil.java:326)
at javax.el.BeanELResolver.invoke(BeanELResolver.java:536)
at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:256)
at com.sun.el.parser.AstValue.invoke(AstValue.java:269)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 35 more
Caused by: java.lang.IllegalArgumentException: Can not set long field com.survey.model.Question.id to java.lang.String
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:164)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:168)
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:55)
at sun.reflect.UnsafeLongFieldAccessorImpl.getLong(UnsafeLongFieldAccessorImpl.java:60)
at sun.reflect.UnsafeLongFieldAccessorImpl.get(UnsafeLongFieldAccessorImpl.java:36)
at java.lang.reflect.Field.get(Field.java:379)
at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:57)
... 76 more

Answer 1

它有点旧，但我遇到了同样的问题。解决方法是拆下转换器。这是不必要的，这导致了问题。我想错误信息是另一个问题