Help with Hibernate mapping

i have the following classes

public class RSS 
{
    private Integer id;
    private String title;
    private String description;
    private String link;
    private Date dateCreated;
    private Collection rssItems;
    private String  url;
    private String language;
    private String rating;
    private Date pubDate;
    private Date lastBuildDate;
    private User user;
    private Date dateModified;

    public RSS() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public void setDescription(String description){
        this.description = description;
    }

    public String getDescription(){
        return this.description;
    }

    public void setLink(String link){
        this.link = link;
    }

    public String getLink(){
        return this.link;
    }

    public void setUrl(String url){
        this.url = url;
    }

    public String getUrl(){
        return this.url;
    }

    public void setLanguage(String language){
        this.language = language;
    }

    public String getLanguage(){
        return this.language;
    }

    public void setRating(String rating){
        this.rating = rating;
    }

    public String getRating(){
        return this.rating;
    }

    public Date getPubDate() {
        return pubDate;
    }

    public void setPubDate(Date pubDate) {
        this.pubDate = pubDate;
    }

    public Date getLastBuildDate() {
        return lastBuildDate;
    }

    public void setLastBuildDate(Date lastBuildDate) {
        this.lastBuildDate = lastBuildDate;
    }

    public Date getDateModified() {
        return dateModified;
    }

    public void setDateModified(Date dateModified) {
        this.dateModified = dateModified;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Collection getRssItems() {
        return rssItems;
    }

    public void setRssItems(Collection rssItems) {
        this.rssItems = rssItems;
    }
}

public class RSSItem {

    private RSS rss;

    private Integer id;
    private String title;
    private String description;
    private String link;
    private Date dateCreated;
    private Date dateModified;
    private int rss_id;

    public RSSItem() {}

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Date getDateModified() {
        return dateModified;
    }

    public void setDateModified(Date dateModified) {
        this.dateModified = dateModified;
    }

    public RSS getRss() {
        return rss;
    }

    public void setRss(RSS rss) {
        this.rss = rss;
    }
}

that i mapped as

    <hibernate-mapping>
  <class name="com.rssFeed.domain.RSS"  schema="PUBLIC" table="RSS">
    <id name="id" type="int">
      <column name="ID"/>
      <generator class="native"/>
    </id>
    <property name="title" type="string">
      <column name="TITLE" not-null="true"/>
    </property>        
    <property name="lastBuildDate" type="java.util.Date">
      <column name="LASTBUILDDATE"/>
    </property>
    <property name="pubDate" type="java.util.Date">
      <column name="PUBDATE" />
    </property>
    <property name="dateCreated" type="java.util.Date">
      <column name="DATECREATED" not-null="true"/>
    </property>
    <property name="dateModified" type="java.util.Date">
      <column name="DATEMODIFIED" not-null="true"/>
    </property>
    <property name="description" type="string">
      <column name="DESCRIPTION" not-null="true"/>
    </property>
    <property name="link" type="string">
      <column name="LINK" not-null="true"/>
    </property>
    <property name="url" type="string">
      <column name="URL" not-null="true"/>
    </property>
    <property name="language" type="string">
      <column name="LANGUAGE" not-null="true"/>
    </property>
    <property name="rating" type="string">
      <column name="RATING"/>
    </property>
     <set inverse="true" lazy="false" name="rssItems">
      <key>
        <column name="RSS_ID"/>
      </key>
      <one-to-many class="com.rssFeed.domain.RSSItem"/>
    </set>
  </class>
</hibernate-mapping>


<hibernate-mapping>
  <class name="com.rssFeed.domain.RSSItem" schema="PUBLIC" table="RSSItem">
    <id name="id" type="int">
      <column name="ID"/>
      <generator class="native"/>
    </id>
    <property name="title" type="string">
      <column name="TITLE" not-null="true"/>
    </property>
    <property name="description" type="string">
      <column name="DESCRIPTION" not-null="true"/>
    </property>
    <property name="link" type="string">
      <column name="LINK" not-null="true"/>
    </property>
    <property name="dateCreated" type="java.util.Date">
      <column name="DATECREATED"/>
    </property>
    <property name="dateModified" type="java.util.Date">
      <column name="DATEMODIFIED"/>
    </property>
    <many-to-one class="com.rssFeed.domain.RSS" fetch="select" name="rss">
      <column name="RSS_ID"/>
    </many-to-one>
  </class>
</hibernate-mapping>

But when i try to fetch an RSS I get the following error

Exception occurred in target VM: failed to lazily initialize a collection of role: com.rssFeed.domain.RSS.rssItems, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.rssFeed.domain.RSS.rssItems, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350) at org.hibernate.collection.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:97) at org.hibernate.collection.PersistentSet.size(PersistentSet.java:139) at com.rssFeed.dao.hibernate.HibernateRssDao.get(HibernateRssDao.java:47) at com.rssFeed.ServiceImplementation.RssServiceImplementation.get(RssServiceImplementation.java:46) at com.rssFeed.mvc.ViewRssController.handleRequest(ViewRssController.java:20) at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:809) 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:734) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:332) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:233) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThre开发者_JAVA百科adPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:619) <

what does it mean?

Thanks

i have modified my code according to the suggestion from Pascal Thivent

and now i get the following exception

type Exception report

message

descriptionThe server encountered an internal error () that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessResourceUsageException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]; nested exception is org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

org.springframework.dao.InvalidDataAccessResourceUsageException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]; nested exception is org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

java.sql.SQLException: Table not found in statement [select rssitems0_.RSS_ID as RSS7_1_, rssitems0_.ID as ID1_, rssitems0_.ID as ID2_0_, rssitems0_.TITLE as TITLE2_0_, rssitems0_.DESCRIPTION as DESCRIPT3_2_0_, rssitems0_.LINK as LINK2_0_, rssitems0_.DATECREATED as DATECREA5_2_0_, rssitems0_.DATEMODIFIED as DATEMODI6_2_0_, rssitems0_.RSS_ID as RSS7_2_0_ from PUBLIC.RSSItem rssitems0_ where rssitems0_.RSS_ID=?]

note The full stack traces of the exception and its root causes are available in the GlassFish v3 logs.

only if i remove the lazyLoad="false" i get the previous error

by the way this is my table definitions

drop table RSS_ITEM if exists
drop table RSS if exists

create table RSS (
   id integer identity primary key,
   title varchar(128) not null, 
   description varchar(2048) not null,
   link varchar(1024) not null,
   url varchar(1024) not null,
   language  varchar(63) not null,
   rating  varchar(63),
   pubDate date,
   lastBuildDate date,
   user_id integer,
   dateCreated date not null,
   dateModified date not null   
);


create table RSS_ITEM (
   id integer identity primary key,
   title varchar(128) not null,
   description varchar(2048) not null,
   link varchar(1024) not null,
   rss_id integer not null,
   dateCreated date not null,
   dateModified date not null   
);


alter table RSS_ITEM add constraint item_rss foreign key (rss_id) references RSS;
alter table RSS add constraint rss_user foreign key (user_id) references RSS_USER;

Basically, a LazyInitializationException is thrown when you try to access a property that is lazy loaded and the Hibernate Session has already been closed (so the property can't be loaded, hence the exception). This is precisely what the trace is reporting about the rssItems property.

The odd part is that you flagged this property with lazy="false" and according to the documentation, this disables lazy fetching and specifies that the association is always eagerly fetched so the rssItems should get eagerly fetched and you shouldn't get a LazyInitializationException.

That being said, I'm not sure the mapping is correct, I'm not sure you can use a <set> when mapping a java.util.Collection. I couldn't find an official reference but if I remember well, you should use a <bag> to map a Collection. So could you try to either:

• change the type of the rssItems property into a java.util.Set ~or~
• change your mapping to use a <bag>

Once done, check if the rssItems get eagerly loaded as expected when you retrieve a RSS entity (activating Hibernate SQL logging would be helpful here).

Your table is named RSS_ITEM in DB but hibernate is looking for RSSItem in SQL query (check error). You need to fix the table name in mapping. Refer you 2nd class mapping in hbm XML. The table name should be RSS_ITEM here.