41 Configuring an Object-Relational Data Type Mapping

41.1 Introduction to Object-Relational Data Type Mapping Configuration

Table 41-1 lists the types of object-relational data type mappings that you can configure and provides a cross-reference to the type-specific chapter that lists the configurable options supported by that type.

For more information, see the following:

• Chapter 17, "Introduction to Mappings"

• Chapter 27, "Introduction to Relational Mappings"

41.2 Configuring Common Object-Relational Data Type Mapping Options

Table 41-2 lists the configurable options shared by two or more object-relational data type mapping types. In addition to the configurable options described here, you must also configure the options described for the specific object-relational data type mapping types (see Section 40.1, "Object-Relational Data Type Mapping Types"), as shown in Table 41-1.

Table 41-2 Common Options for Object-Relational Data Type Mappings

Option to Configure	Oracle JDeveloper	TopLink Workbench	Java
Reference class (see Section 41.3, "Configuring Reference Class")
Attribute name (see Section 41.4, "Configuring Attribute Name")
Field name (see Section 41.5, "Configuring Field Name")
Structure name (see Section 41.6, "Configuring Structure Name")
Read-only (see Section 121.2, "Configuring Read-Only Mappings")
Method or direct field access (see Section 121.6, "Configuring Method or Direct Field Accessing at the Mapping Level")
Indirection (lazy loading) (see Section 121.3, "Configuring Indirection (Lazy Loading)")
Container policy (see Section 121.14, "Configuring Container Policy")

41.3 Configuring Reference Class

When mapping an attribute that involves a relationship to another class, you must specify the reference class–the Java class to which the mapped attribute refers.

Table 41-3 summarizes which object-relational data type mappings support this option.

public void customize(ClassDescriptor descriptor) { 
    ReferenceMapping managerMapping = new ReferenceMapping();

    managerMapping.setReferenceClass("Employee.class"); // set reference class
    managerMapping.setAttributeName("manager");

    // add this mapping to descriptor
    descriptor.addMapping(managerMapping);
}

41.4 Configuring Attribute Name

All object-relational data type mappings map an attribute in a Java object to field in the database. The attribute name is the name of the attribute being mapped. The name is as specified in the reference class (see Section 41.3, "Configuring Reference Class").

Table 41-4 summarizes which object-relational data type mappings support this option.

Table 41-4 Mapping Support for Attribute Name

Mapping	How to Use Oracle JDeveloper	How to Use TopLink Workbench	How to Configure Attribute Name Using Java
Object-relational data type structure mapping (see Section 40.1.1, "Object-Relational Data Type Structure Mapping")
Object-relational data type reference mapping (see Section 40.1.2, "Object-Relational Data Type Reference Mapping")
Object-relational data type array mapping (see Section 40.1.3, "Object-Relational Data Type Array Mapping")
Object-relational data type object array mapping (see Section 40.1.4, "Object-Relational Data Type Object Array Mapping")
Object-relational data type nested table mapping (see Section 40.1.5, "Object-Relational Data Type Nested Table Mapping")

public void customize(ClassDescriptor descriptor) { 
    ReferenceMapping managerMapping = new new ReferenceMapping();
    managerMapping.setReferenceClass("Employee.class"); 
    managerMapping.setAttributeName("manager"); // set attribute name

    // add this mapping to descriptor
    descriptor.addMapping (managerMapping);
}

41.5 Configuring Field Name

All object-relational data type mappings require the name of database field to which their specified attribute is mapped. This field name can be the column name of a database table or the name of a field in an object type created on the database.

Table 41-5 summarizes which object-relational data type mappings support this option.

public void customize(ClassDescriptor descriptor) { 
    ObjectArrayMapping phonesMapping = new ObjectArrayMapping();
    phonesMapping.setReferenceClass("Employee.class");
    phonesMapping.setAttributeName("phone");
    phonesMapping.setFieldName("PHONE_NUMBER"); // set field name

    // add this mapping to descriptor
    descriptor.addMapping (phonesMapping);
}

41.6 Configuring Structure Name

Certain object-relational data type mappings require the specification of the data type or structure name of the field being mapped. The structure name is the name of the array or table type that defines the field.

Table 41-6 summarizes which object-relational data type mappings support this option.

public void customize(ClassDescriptor descriptor) { 
    ObjectArrayMapping phonesMapping = new ObjectArrayMapping();
    phonesMapping.setReferenceClass("Employee.class");
    phonesMapping.setAttributeName("phones");
    phonesMapping.setFieldName("PHONE_NUMBERS");
    phonesMapping.setStructureName("PHONE_ARRAY_TYPE"); // set structure name

    // add this mapping to descriptor
    descriptor.addMapping (phonesMapping);
}