java - Mapping same class relation - continuation

Question

This post is an continuation of this post

I have DlUser Class each object of this class may have DLFaceBook class and each object of DlFaceBook can have Friends which are mapped as myFriends.

I'm trying to map relation of the same class as many to many relation using bag mapping,composite primary key and static inner class. my code is the following:

public class DlUser{
 public DlUser(){}
 Long Id;
 String FirstName;
 String LastName;
 ....
 DlFaceBook fbuser;
 //// all requred 
 getters and setters...
}

The Facebook user class looks like this as you can see I have the collection of objectes with the class MyFriends:

public class DlFaceBook {
private long dlpId;
private String FbId;
private Collection<MyFriends> Friends;
public DlFaceBook(){}
public void setFbId(String FbId)
{
    this.FbId = FbId;
}
public void setFriends(Collection<MyFriends> friends)
{
    this.Friends = friends;
}
public Collection<MyFriends> getFriends()
{
    return this.Friends;
}
public void setdlpId(long id)
{
    this.dlpId = id;
}
public long getdlpId()
{
    return this.dlpId;
}
public String getFbId()
{
    return this.FbId;
}
}

MyFriends class looks like this:

public class MyFriends {

    private MyFriendsId myFriendId;

    private DlFaceBook me;
    private DlFaceBook myFriend;
   public MyFriendsId getmyFriendId(){
        return this.myFriendId;
   }
   public void setmyFriendId(MyFriendsId fid){
    this.myFriendId = fid;
   }

    public void setme(DlFaceBook me){
      this.me = me;
   }
   public void setmyFriend(DlFaceBook friend){
          this.myFriend = friend;
       }
   public DlFaceBook getme(){
          return this.me ;
       }
       public DlFaceBook getmyFriend(){
              return this.myFriend ;
           }
    public MyFriends(DlFaceBook me, DlFaceBook user){
        this.me = me ;
        this.myFriend = user;
        this.myFriendId = new MyFriendsId(me.getdlpId(),user.getdlpId());
    }
    public static class MyFriendsId implements Serializable {

        private long meId;
        private long myFrId;

        // getter's and setter's

        public MyFriendsId() {}
        public MyFriendsId(long meId, long myFriendId) {
            this.meId = meId;
            this.myFrId = myFriendId;
        }

        // getter's and setter's
        public long getmeId(){
            return this.meId;
        }
        public void setmeId(Integer id){
            this.meId = id;
        }

        public long getmyFrId(){
            return this.myFrId;
        }
        public void setmyFrId(long id){
            this.myFrId = id;
        }
    }
} 

Now the Mapping:

DlUser.hbm.xml is the following and it's simple:

<hibernate-mapping>
  <class name="DlUser" table="Users">
  <id name="Id" column="id" >
<generator class="sequence">
                <param name="sequence">userseq</param>
            </generator>        
 </id>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
 <property name="firstName">
     <column name="FirstName" />
  </property>
  <property name="lastName">
    <column name="LastName"/>
  </property>
 <many-to-one
            name="FaceBook"
            class="DlFaceBook"
            cascade="all"
            column="dlpId"
            unique="true" 
        />
 </class>
</hibernate-mapping>

DlFacebook.hbm.xml looks like this:

<hibernate-mapping>
  <class name="DlFaceBook" table="dlfacebook">
 <id name="dlpId" type="java.lang.Long" column="dlpId">
<generator class="increment" />
</id>
   <property name="fbId">
     <column name="fbId" />
  </property>
     <bag name="Friends"> 
            <key column="me_Id" />
            <one-to-many class="MyFriends"/>
        </bag>
 </class>
</hibernate-mapping>

Then MyFriends.hbm.xml looks like this:

<hibernate-mapping>
  <class name="MyFriends">
  <composite-id name="myFriendId" class="MyFriends$MyFriendsId">
        <key-property name="meId"/>
        <key-property name="myFrId"/>
    </composite-id>
    <many-to-one name="me" class="DlFaceBook" insert="false" update="false"/>
    <many-to-one name="myFriend" class="DlFaceBook" insert="false" update="false"/>
    </class>
    </hibernate-mapping>

When I'm executing my query I got the following error:

Hibernate: insert into dlfacebook (fbId, dlpId) values (?, ?)
Hibernate: insert into Users (FirstName, LastName, email, twitter, birthday, dlpId, id) values (?, ?, ?, ?, ?, ?, ?)
Hibernate: update MyFriends set me_Id=? where meId=? and myFrId=?
Hibernate: update MyFriends set me_Id=? where meId=? and myFrId=?
Oct 2, 2010 1:21:18 PM org.hibernate.jdbc.BatchingBatcher doExecuteBatch
SEVERE: Exception executing batch: 
org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1
    at org.hibernate.jdbc.Expectations$BasicExpectation.checkBatched(Expectations.java:85)
    at org.hibernate.jdbc.Expectations$BasicExpectation.verifyOutcome(Expectations.java:70)
    at org.hibernate.jdbc.BatchingBatcher.checkRowCounts(BatchingBatcher.java:90)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:183)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206)
    at Test.main(Test.java:54)
Oct 2, 2010 1:21:18 PM org.hibernate.event.def.AbstractFlushingEventListener performExecutions
SEVERE: Could not synchronize database state with session
org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1
    at org.hibernate.jdbc.Expectations$BasicExpectation.checkBatched(Expectations.java:85)
    at org.hibernate.jdbc.Expectations$BasicExpectation.verifyOutcome(Expectations.java:70)
    at org.hibernate.jdbc.BatchingBatcher.checkRowCounts(BatchingBatcher.java:90)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:183)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206)
    at Test.main(Test.java:54)
Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

I see that this error happens when we trying to update not existing row, but how can I make this code work?

Answer 1

Just Facebook and MyFriends

Facebook Notice add convenience method and MutableLong (later, i tell you why to use MutableLong)

public class Facebook {

    private MutableLong id = new MutableLong();
    public Long getId() { return id.longValue(); }
    public void setId(Long id) { this.id.setValue(id); }

    public MutableLong getIdAsMutableLong() {
        return id;
    }

    private Collection<MyFriends> myFriends = new ArrayList<MyFriends>();
    public Collection<MyFriends> getMyFriends() { return myFriends; }
    public void setMyFriends(Collection<MyFriends> myFriends) { this.myFriends = myFriends; }

    /**
     * add convenience method
     */
    public void addFriend(Facebook myFriendFacebook) {
        myFriends.add(new MyFriends(this, myFriendFacebook));
    }

}

MyFriends

public class MyFriends {

    private MyFriendsId myFriendId;
    public MyFriendsId getmyFriendId(){ return this.myFriendId; }
    public void setmyFriendId(MyFriendsId myFriendId){ this.myFriendId = myFriendId; }

    private Facebook me;
    public Facebook getme() { return this.me; }
    public void setme(Facebook me){ this.me = me; }

    private Facebook myFriend;
    public Facebook getmyFriend() { return this.myFriend; }
    public void setmyFriend(Facebook friend) { this.myFriend = friend; }

    public MyFriends() {}
    public MyFriends(Facebook meFacebook, Facebook myFriendFacebook){
        this.me = meFacebook ;
        this.myFriend = myFriendFacebook;

        this.myFriendId = new MyFriendsId(meFacebook.getIdAsMutableLong(), myFriendFacebook.getIdAsMutableLong());
    }

    public static class MyFriendsId implements Serializable {

        private MutableLong meId = new MutableLong();
        public Long getMeId() { return this.meId.longValue(); }
        public void setMeId(Long id) { this.meId.setValue(id); }

        private MutableLong myFriendId = new MutableLong();
        public Long getMyFriendId(){ return this.myFriendId.longValue(); }
        public void setMyFriendId(Long id) { this.myFriendId.setValue(id); }

        public MyFriendsId() {}
        public MyFriendsId(MutableLong meId, MutableLong myFriendId) {
            this.meId = meId;
            this.myFriendId = myFriendId;
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof MyFriendsId))
                return false;

            MyFriendsId other = (MyFriendsId) o;
            return new EqualsBuilder()
                       .append(getMeId(), other.getMeId())
                       .append(getMyFriendId(), getMyFriendId())
                       .isEquals();
        }

        @Override
        public int hashCode() {
            return new HashCodeBuilder()
                       .append(getMeId())
                       .append(getMyFriendId())
                       .hashCode();
        }

    }
}

Mapping

<hibernate-mapping package="br.com._3845772.model.domain">
    <class name="User">
        <id name="id">
            <generator class="native"/>
        </id>
        <many-to-one cascade="all" class="Facebook" name="facebook"/>
    </class>
    <class name="Facebook">
        <id name="id">
            <generator class="native"/>
        </id>
        <bag cascade="all" name="myFriends">
            <key column="ME_FACEBOOK_ID" update="false"/>
            <one-to-many class="MyFriends"/>
        </bag>
    </class>
    <class name="MyFriends">
        <composite-id class="MyFriends$MyFriendsId" name="myFriendId">
            <key-property column="ME_FACEBOOK_ID" name="meId"/>
            <key-property column="MY_FRIEND_FACEBOOK_ID" name="myFriendId"/>
        </composite-id>
        <many-to-one class="Facebook" column="ME_FACEBOOK_ID" insert="false" name="me" update="false"/>
        <many-to-one class="Facebook" column="MY_FRIEND_FACEBOOK_ID" insert="false" name="myFriend" update="false"/>
    </class>
</hibernate-mapping>

And this sample

Facebook meFacebook = new Facebook();
Facebook myFriendFacebook = new Facebook();

meFacebook.addFriend(myFriendFacebook);

Session session = sessionFactory.openSession();
session.beginTransaction();

session.save(myFriendFacebook);
session.save(meFacebook);

session.getTransaction().commit();
session.close();

Which gives me

Hibernate: insert into Facebook values ( )
Hibernate: insert into Facebook values ( )
Hibernate: select myfriends_.ME_FACEBOOK_ID, myfriends_.MY_FRIEND_FACEBOOK_ID from MyFriends myfriends_ where myfriends_.ME_FACEBOOK_ID=? and myfriends_.MY_FRIEND_FACEBOOK_ID=?
Hibernate: insert into MyFriends (ME_FACEBOOK_ID, MY_FRIEND_FACEBOOK_ID) values (?, ?)

A couple of notes

• Hibernate does not support automatic generation of composite primary key. You must set up its value before saving
• Your database must support the target generator strategy (If you does not know which generator strategy your database support, prefer to use a native strategy)
• Each entity must supply a no-arg constructor

Now why MutableLong (encapsulated by a Long property) instead of Long ?

Number and its subclasses (Long is a Number) are immutable. So if you want Facebook.id (configured by database) and its counterpart MyFriend$MyFriendId.meId share the same value, you must use MutableLong. When the database set up Facebook.id, MyFriend$MyFriendId.meId automatically get its newest value. But it just occurs if you use a MutableLong.