Configuring Private or Independent Relationships

In TopLink, object relationships can be either private or independent.

• In a private relationship, the target object is a private component of the source object. The target object cannot exist without the source and is accessible only through the source object. Destroying the source object will also destroy the target object.

• In an independent relationship, the source and target objects are public ones that exist independently. Destroying one object does not necessarily imply the destruction of the other.

Tip: TopLink automatically manages private relationships. Whenever an object is written to the database, any private objects it owns are also written to the database. When an object is removed from the database, any private objects it owns are also removed. Be aware of this when creating new systems, since it may affect both the behavior and the performance of your application.

Table 35-8 summarizes which mappings support this option.

Table 35-8 Mapping Support for Private or Independent Relationships

Mapping	Implicitly Private	Private or Independent	Using TopLink Workbench	Using Java
Relational Mappings
One-to-One Mapping
Variable One-to-One Mapping
One-to-Many Mapping
Many-to-Many Mapping
Aggregate Collection Mapping
Direct Collection Mapping
Direct Map Mapping
Aggregate Object Mapping
Object-Relational Mappings
Object-Relational Structure Mapping
Object-Relational Reference Mapping
Object-Relational Array Mapping
Object-Relational Object Array Mapping
Object-Relational Nested Table Mapping
EIS Mappings
EIS Composite Direct Collection Mapping
EIS Composite Object Mapping
EIS Composite Collection Mapping
EIS One-to-One Mapping
EIS One-to-Many Mapping
XML Mappings
XML Composite Direct Collection Mapping
XML Composite Object Mapping
XML Composite Collection Mapping

Using TopLink Workbench

To create a privately owned mapping, use this procedure:

1. Select the mapped attribute in the Navigator. Its properties appear in the Editor.

2. Click the General tab. The General tab appears.

   Figure 35-8 General tab, Private Owned option

   
   Description of "Figure 35-8 General tab, Private Owned option"
   
   

To create private ownership, select the Private Owned option.

Using Java

For mappings not supported in TopLink Workbench, use the independentRelationship (default), privateOwnedRelationship, and setIsPrivateOwned methods.

Example 35-9 shows how to use these methods with a class that has a privately owned attribute, phones, in a mapping.

Example 35-10 Configuring Access Method in Java

// Map the phones attribute
phonesMapping.setAttributeName("phones");
 
// Specify as privately owned
phonesMapping.privateOwnedRelationship();