Having trouble in understanding bi directional relationships

[Kumar Raja]

Hello All,

To be honest with you, I have spent considerable amount of time in understanding the associations (specially bidirectional) but still not really able to understand the basics. I could not get a simple one to many bidirectional mapping to work and I need your help in understanding the mistake and a fix.

I have two classes Stock and StockDailyRecords. (These examples are taken straightly from example. My stock class is defined as below

    
       public class Stock{
          private int id;
          ...........
          ...........
          private Set<StockDailyRecord> sdr=new HashSet<StockDailyRecord>();
          //Followed by setters and getters

Similarly StockDailyRecord is as follows

    
       public class Stock{
          private int id;
          ...........
          ...........
          private Stock stock=null;
          //Followed by setters and getters

My entire mapping files are as below
Stock.hbm.xml

    
<hibernate-mapping package="com.hibertut.beans">
	<class name="Stock" table="STOCK" >
		<id name="id" column="STOCK_ID" type="long">
			<generator class="native" />
		</id>
                                ...............................................
                                ...............................................
		<set name="sdr" table="STOCK_DAILY_RECORD">
			<key column="STOCK_FK_ID" not-null="true" />
			<one-to-many class="StockDailyRecord" />
		</set>
	</class>
</hibernate-mapping>

StockDailyRecord.hbm.xml

    
<hibernate-mapping package="com.hibertut.beans">
	<class name="StockDailyRecord" table="STOCK_DAILY_RECORD" >
		<id name="id" column="DAILY_RECORD_ID" type="int">
			<generator class="native" />
		</id>
                                 .............................................
                                 .............................................
		<many-to-one name="stock" unique="true" class="Stock"
			column="STOCK_FK_ID" not-null="true" />
	</class>
</hibernate-mapping>

I'm facing two issues here
1) if I have same column in Set element of Stock and Many to One element of StockDailyRecord, I'm getting an exception

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.hibertut.beans.StockDailyRecord column: STOCK_FK_ID (should be mapped with insert="false" update="false"). 

I'm not sure why I should make insert and update false here.

If I manage to change the name of the either of the columns say, from STOCK_FK_ID to STOCK_ID (Which does not make any sense to me here? Why?), I get another error

Exception in thread "main" org.hibernate.PropertyValueException: not-null property references a null or transient value: com.hibertut.beans.StockDailyRecord._com.hibertut.beans.Stock.sdrBackref

while trying to persist Stock and StockDailyRecord.

My client looks like below

    
HiberTut hiber=new HiberTut();
		Stock s1=new Stock();
		StockDailyRecord sdr=new StockDailyRecord();
		s1.setStockCode(123);
		s1.setStockName("Satyam");
		sdr.setClose(50.5);
		sdr.setOpen(45.5);
		hiber.create(s1);
		sdr.setStock(s1);
		hiber.create(sdr);
		s1.getSdr().add(sdr);

create(Object) method looks as below

public Object create(Object obj){
		session=sessionFactory.openSession();
		Transaction trans=session.beginTransaction();
		Object ret=null;;
		trans.begin();
		ret=session.save(obj);
		trans.commit();
		session.flush();
		session.close();
		return ret;
	}

How do I persist both the records. When I run my client, I'm successful in persisting only Stock, but not StockDailyRecord. How do I make sure that upon persisting Stock, it should also persist StockDailyRecord without using Cascase option.

Does it make any difference in using "inverse" attribute ?

Please help me

[Kumar Raja]

Can some body take a look at my question and help me understand that ?