I have a hibernate and JSF2 application going to the deployment server and suddenly throwing an org.hibernate.AssertionFailure: null id in exception. I will provide the stack trace and code immediately but here are four important issues first:

Researching this, it seems that people get this error when trying to insert an object. But I get the error when I'm doing a simple query. (various different queries, actually, as the error pops up on several pages randomly.)

The error hits only every now and then. If I do a Jboss restart it goes away, but a time later returns. Also, it's not consistent, on some clicks it's there, on others it's not. Even when it hits, when I do a simple refresh of the page it returns fine.

I'm using c3p0 (config below)

Any idea what's going on?

The code details:

This happens on an address object. Here's the full hbm:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.idex.auctions.model">
<class name="Address" table="address" lazy="true">

<id name="addressID" column="AddressID">
<generator class="native"/>
</id>

<property name="street" column="street"/>
<property name="city" column="city"/>
<property name="zip" column="zip"/>
<property name="state" column="state"/>
<property name="region" column="region"/>
<property name="country" column="country"/>

<many-to-one name="user" class="com.idex.auctions.model.User" column="userid" unique="true" cascade="save-update"/>

</class>
</hibernate-mapping>

The java class is straight forward:

public class Address implements Serializable {
private static final long serialVersionUID = 7485582614444496906L;

private long addressID;
private String street;
private String city;
private String zip;
private String state;
private String region;
private String country;
private User user;

public Address() {

}
public long getAddressID() {
return addressID;
}
public void setAddressID(long addressID) {
this.addressID = addressID;
}
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getRegion() {
return region;
}
public void setRegion(String region) {
this.region = region;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}

}

The c3p0 configuration:

<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">1000</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.timeout">1800</property>
<property name="hibernate.c3p0.max_statements">0</property>
<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

The versions used are

hibernate3.jar

c3p0-0.9.1.2.jar

myfaces-api-2.1.4.jar

myfaces-impl-2.1.4.jar

mysql-connector-java-5.1.20-bin.jar

Now the full stacktrace (sorry, for some reason it's not getting the pretty print when doing the 4 spaces thing):

org.hibernate.AssertionFailure: null id in com.idex.auctions.model.Address entry (don't flush the Session after an exception occurs)
org.hibernate.event.def.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:78)
org.hibernate.event.def.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:187)
org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:143)
org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:219)
org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:99)
org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:58)
org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:997)
org.hibernate.impl.SessionImpl.list(SessionImpl.java:1142)
org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
com.idex.auctions.manager.DatabaseManager.getAllObjects(DatabaseManager.java:464)
com.idex.auctions.ui.NavBean.gotoHome(NavBean.java:40)
sun.reflect.GeneratedMethodAccessor350.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
javax.el.BeanELResolver.invokeMethod(BeanELResolver.java:735)
javax.el.BeanELResolver.invoke(BeanELResolver.java:467)
javax.el.CompositeELResolver.invoke(CompositeELResolver.java:246)
org.apache.el.parser.AstValue.getValue(AstValue.java:159)
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
org.apache.myfaces.view.facelets.el.ContextAwareTagValueExpression.getValue(ContextAwareTagValueExpression.java:96)
javax.faces.component._DeltaStateHelper.eval(_DeltaStateHelper.java:246)
javax.faces.component.UIOutcomeTarget.getOutcome(UIOutcomeTarget.java:50)
org.apache.myfaces.shared.renderkit.html.HtmlRendererUtils.getOutcomeTargetHref(HtmlRendererUtils.java:1542)
org.apache.myfaces.shared.renderkit.html.HtmlLinkRendererBase.renderOutcomeLinkStart(HtmlLinkRendererBase.java:908)
org.apache.myfaces.shared.renderkit.html.HtmlLinkRendererBase.encodeBegin(HtmlLinkRendererBase.java:143)
javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:502)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:744)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:758)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:758)
org.apache.myfaces.view.facelets.FaceletViewDeclarationLanguage.renderView(FaceletViewDeclarationLanguage.java:1900)
org.apache.myfaces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:285)
com.ocpsoft.pretty.faces.application.PrettyViewHandler.renderView(PrettyViewHandler.java:163)
javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:59)
org.apache.myfaces.tomahawk.application.ResourceViewHandlerWrapper.renderView(ResourceViewHandlerWrapper.java:93)
com.idex.auctions.ui.CustomViewHandler.renderView(CustomViewHandler.java:98)
org.apache.myfaces.lifecycle.RenderResponseExecutor.execute(RenderResponseExecutor.java:115)
org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:241)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:199)
com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:126)
com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:118)

My guess is that sessions are re-used between requests instead of creating a new one for each request. So, when you see the exception it is because the same session was previously used in a situation that resulted in an exception (and then it must be discarded and not used again). When you click refresh and it works it is just that the new request is executing in a different thread with a different session that is still working. That is also why a server restart seems to fix everything, since no session has become corrupted yet.

Thank you very much for this, nordborg. So how do I solve this?

Just to make sure I'm doing the right thing, here's my typical use of hibernate:

public static List<LoggedInUser> findAllLoggedInUsers() {
String sql = "FROM com.auctions.model.LoggedInUser order by userId, loggedInTime desc";
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
List<LoggedInUser> LoggedInUsers = (List<LoggedInUser>)session.createQuery(sql).list();
session.getTransaction().commit();
return LoggedInUsers;
}

Is this correct?

And in any case, how would I make sure to discard the hibernate session once there's an exception in it?

Anyone? What nordborg says sounds right but I need a bit more help here :) Can anyone point me in the right direction?

One popular pattern used in this kind of scenario is the "Open session in view" pattern. It uses a ServletFilter to handle the opening and closing of the session for each request. Typically, the transaction is also handled here. Starting and committing a transaction programmatically in the DAO methods (such as your findAllLoggedInUsers) is considered an anti-pattern (since now that piece of code can't be reused in a different use case that may need a transaction that spans multiple method calls).

In any case, there is a wiki page on the JBOSS community describing the Open-session-in-view pattern: https://community.jboss.org/wiki/OpenSessionInView

It's a bit old and some details may be different in more recent Hibernate versions, but the overall concept should be the same.