How to insert a new child record only. One to Many Relation.

[Ajay Luthria]

a).I have a Trade object which can have multiple status's. One to Many relationship

-----------------------------------------------------
Trade                  TradeDetails
------                 ------------
ID                       ID  STATUS  TRADE_ID(Foreign Key)
---                      -----------------------------------
1                         1  New           1
                           2  Verified       1
                           3  Executed     1
-----------------------------------------------------
Create table trade(
id INT NOT NULL AUTO_INCREMENT,
PRIMARY KEY(id)
);


CREATE TABLE tradedetails(
id INT NOT NULL AUTO_INCREMENT,
status VARCHAR(20),
trade_id INT NOT NULL,
PRIMARY KEY(id),
FOREIGN KEY(trade_id) REFERENCES trade(id)
);

b.Now,I have inserted a new record with a status of 'New' in the parent(Trade) and child (TradeDetails) tables.
This works fine.(Code is attached below).

c.My Query is:

Now 3 days later, I want to enter a new record in the child table with the same 'parent id'
and status set to 'Verified'.

How can I insert a new record only in the child table with the status set to 'Verified'
and then another with the status set to 'Executed' for the same parent?

i.e 1 Parent - 3 Children entered on different times.

I hope I am clear in my query.

My code to create a new record in Parent and child is below.

Trade.hbm.xml
-------------
<hibernate-mapping>
  
<class name="hibernate.Trade" table="TRADE">
    
        <id name="id" column="ID">
            <generator class="native"/>
        </id>
        
        <set name="statuses" cascade="all" inverse="true" lazy="true">
			<key column="trade_id"/>
			<one-to-many class="hibernate.TradeDetails"/>
		</set> 		
       
 </class>

</hibernate-mapping>

TradeDetails.hbm.xml
--------------------
<hibernate-mapping>
  
<class name="hibernate.TradeDetails" table="TRADEDETAILS">
    
        <id name="id" column="ID">
            <generator class="native"/>
        </id>
        
        <property name="status"/>
        
        <many-to-one name="trade" class="hibernate.Trade" column="trade_id" not-null="true"/>
       
</class>

</hibernate-mapping>


Hibernate,cfg.xml
-----------------
<hibernate-configuration>
<session-factory>
      <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
      <property name="hibernate.connection.url">jdbc:mysql://localhost/test</property>
      <property name="hibernate.connection.username">root</property>
      <property name="hibernate.connection.password">bhuru</property>
      <property name="hibernate.connection.pool_size">10</property>
      <property name="show_sql">true</property>
      <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
      <property name="hibernate.hbm2ddl.auto">update</property>
      
      <!-- Mapping files -->
      
      <mapping resource="Trade.hbm.xml"/>
      <mapping resource="TradeDetails.hbm.xml"/> 
 
      
      
      
</session-factory>
</hibernate-configuration>

Java Code
--------
public class Trade {

	private Long id;
	private Set statuses = new HashSet();

    // Constructor
    public Trade(){}

    public Long getId() {
        return id;
    }

    private void setId(Long id) {
	        this.id = id;
    }
    
    public void setStatuses(Set l) {
    	statuses = l;
   	}
   
    public Set getStatuses() {
    	return statuses;
    }


}

TradeDetails.java
-----------------
public class TradeDetails {
	
	private Long id;
	private String status;
	private Trade trade;
		
	 // Constructor
    public TradeDetails(/*String status*/){
    	//this.status = status;
    	//this.trade  = trade;
    }

    public Long getId() {
        return id;
    }

    private void setId(Long id) {
	   this.id = id;
    }
    
    public void setStatus(String status) {
    	this.status=status;
    }
    
    public String getStatus() {
    	return status;
    }

    public void setTrade(Trade trade){
    	this.trade = trade;
    }

    public Trade getTrade(){
    	return trade;
    }

}

Test Harness
-----------
public class OneToMany_Test {

	public static void main(String[] args) {
	
		Configuration configuration = new Configuration();
        SessionFactory  sessionFactory = configuration.configure().buildSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();
       
        // Parent.
        Trade trade = new Trade();
       
        // Child.
        TradeDetails tDetails = new TradeDetails();
        tDetails.setStatus("New");
        tDetails.setTrade(trade);
       
        // Create a sey of status
        Set setOfStatus = new HashSet();
        setOfStatus.add(tDetails);
        
        // Add to Parent.
        trade.setStatuses(setOfStatus);

        // Save Parent.
        session.save(trade);
        
        // Commit Record.
        transaction.commit();


		
		
	} // end main()
	
	
	

} // end class

[Cameron Wallace McKenzie]

Load the Parent, add the child to the parent, save them both.

The use of terms "parent" and "child" always seem awkward with their different meaning from parent and child in object models.

-Cameron McKenzie