Exception in JSP when populating a table with list

Question

I have this jsp code .

<c:forEach var="item" items="${UsersList}">
 <tr>
 <td><c:out value="${item.userId}" /></td>
 <td><c:out value="${item.userName}" /></td>
 <td><c:out value="${item.car}" /></td>  //Here , I am getting exception
 </tr>
 </c:forEach>

The UserList consists of an attribute called "car" of datatype "Car"

Pojo Class class for Users:

@Entity
@Table(name = "Users")
public class Users implements java.io.Serializable {

private int userId;
private Car car;
private Groups groupId;
private UserType userType;
private String userName;

//getters and setters
}

I am using Spring MVC Framework. On page load my app should show a table with the list of users . In controller I am querying for the list of users and I am adding it to the ModelAndView object

Controller code:

List<Users> userList = service.getUserList();  //this will get list of users
//System.out.println("Userlist ==" +userList.size()); 
mv.addObject("UsersList" , usersList);
//skipped remaining code

When I tried without car (tabledata tag) JSP is running without exception and showing the users list in the table . If I try to add car (tabledata tag) then I am getting an exception

HTTP Status 500 - An exception occurred processing JSP page /WEB-INF/pages/CreateUser.jsp at line 199 
org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/pages/CreateUser.jsp at line 199

196:<tr>
197:<td><c:outvalue="${item.userId}" /></td>
198:<td><c:out value="${item.userName}" /></td>
199:<!-- <td><c:out value="${item.car}" /></td> --> 
200:<td><c:out value="${item.modifiedDate}" /></td>
201:</tr>
202:</c:forEach>                                            


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWra    pper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:4    70)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutput    Model(InternalResourceView.java:168)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:3    03)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.j    ava:1244)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(Disp    atcherServlet.java:1027)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServl    et.java:971)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServle    t.java:893)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkSer    vlet.java:970)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java    :861)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.ja    va:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
root cause

org.hibernate.LazyInitializationException: could not initialize proxy - no  Session
org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:149)
org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:195)
org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)
com.bdp.pojo.Role_$$_javassist_11.toString(Role_$$_javassist_11.java)
org.apache.taglibs.standard.tag.common.core.OutSupport.out(OutSupport.java:178)
org.apache.taglibs.standard.tag.common.core.OutSupport.doStartTag(OutSupport.java:99)
org.apache.jsp.WEB_002dINF.pages.CreateUser_jsp._jspx_meth_c_005fout_005f2(CreateUser_jsp.java:667)
org.apache.jsp.WEB_002dINF.pages.CreateUser_jsp._jspx_meth_c_005fforEach_005f0(CreateUser_jsp.java:591)
org.apache.jsp.WEB_002dINF.pages.CreateUser_jsp._jspService(CreateUser_jsp.java:264)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:168)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframeweb.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

Sercan Ozdemir · Answer 1 · 2015-12-18T15:27:40.470

3

Since you are using hibernate lazy initialization, whenever you return the main object to the JSP it will try to fetch sub classes. And this wont happen because session would be closed.

Therefore change your fetching strategy to the Eager:

On your car's getter method:

@OneToOne(fetch=FetchType.EAGER)

This will cause fetching car immediatly when you fetch the main class.

To make it on query:

 List<Users> items = session.createCriteria(Users.class)
                    .setFetchMode("car", FetchMode.JOIN).
                    .createAlias("car", "car").
                    .list();

edited Dec 18 '15 at 15:27

answered Dec 18 '15 at 13:55

Sercan Ozdemir

4,641
3
34
64

I tried doing that way . But , It is reflecting on entire project. I am getting Exceptions. – no1 Dec 18 '15 at 14:31
1

What do you mean by "Exceptions". You can change fetch strategy during executing of query – Sercan Ozdemir Dec 18 '15 at 14:32
Ohh !! I don't know that one . Can you give any good reference for that. – no1 Dec 18 '15 at 14:33

ooozguuur · Answer 2 · 2015-12-18T14:42:29.783

1

You receive error LazyInitializationException. Users objects in a lazy Car object. service.getuserlist(); method can bring in by fetch the Car objects.

Fetching Strategies

FetchType.LAZY is on demand

FetchType.EAGER is immediate

@OneToOne(fetch=FetchType.EAGER) when you do want to take the user object as object the car all the time.

service.getUserList () please write.

EDIT :

Example getUserList method:

public List<Users> getUserList(){
    String sql = " SELECT user from Users user left join fetch user.car ";
    Query query = entityManager.createQuery(sql);
    return query.getResultList();
}

edited Dec 18 '15 at 14:42

answered Dec 18 '15 at 14:17

ooozguuur

3,396
2
24
42

I tried your query but I din't got the actual value. I got an object like this `com.project.pojo.Car@74b02890` – no1 Dec 18 '15 at 15:03
this com.project.pojo.Car@74b02890 proxy object. See http://stackoverflow.com/a/25340780/1638718 – ooozguuur Dec 18 '15 at 15:43
No error bro :) but not displaying the value .. displaying that object – no1 Dec 18 '15 at 16:56
Please write car object. – ooozguuur Dec 18 '15 at 22:16
Car Pojo Class write. – ooozguuur Dec 21 '15 at 09:10

Exception in JSP when populating a table with list

2 Answers2