@OneToMany new reference table is generated.

[Chandra Bhatt]

Hi,

I have OrderMain table and OrderItems tables with @OneToMany relationship in them. I set table schema to be generated automatically.
It generates a third reference table named OrderMain_OrderItems containing id from the OrderMain and OrderItems.
I wanted to have the Foreign Key to be there in OrderItems table referring OrderMain table id (PK).
Is there any setting to avoid the third referencing table and have the FK on the target side of the relationship.

[Jeanne Boyarsky]

Chandra,
Can you show the code? What you describe makes sense for a many to many relationship. I'm surprised to see it for a one to many.

[Chandra Bhatt]

Jeanne,

Below is the code I used:

@Entity   
public class Order_Main {
private static final long serialVersionUID = 1L;
    private Long id;
    private String customer_name;
    private List<Order_Items> items;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }        
....
....

@OneToMany(cascade={CascadeType.ALL})
    public List<Order_Items> getItems() {
        return items;
    }
}

    

public class Order_Items {
private static final long serialVersionUID = 1L;
    private Long id;
    private String item_name;
    private Double qty;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }
}

persistence.xml

    
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="hello-world" transaction-type="RESOURCE_LOCAL">
<provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
<class>orderbeans.Order_Main</class>
<class>orderbeans.Order_Items</class>
<properties>
<property name="toplink.jdbc.url" value="jdbc:mysql://localhost:3306/minerva"/>
<property name="toplink.jdbc.user" value="root"/>
<property name="toplink.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="toplink.jdbc.password" value="password"/>
<property name="toplink.ddl-generation" value="drop-and-create-tables"/>
</properties>
</persistence-unit>
</persistence>

Thanks

[Jeanne Boyarsky]

Chandra,
Usually when I create a @OneToMany relationship, it is bi-directional. This would mean Order_Items would point to Order_Main.

The TopLink documentation says "configure the details of the join table used by TopLink JPA for uni-directional one-to-many relationships". Maybe the join table is being created in your example because Order_Main isn't being told which table Order_Items is in?

[Chandra Bhatt]

thanks Jeanne