Writing Mappings in Code

Example 3-50 Implementing Descriptors for the Classes in the Inheritance Hierarchy

// Vehicle is a root class. Because it is the root class, it must add the class 
// indicators for its subclasses.
public static Descriptor descriptor() 
{
    Descriptor descriptor = new Descriptor();
    descriptor.setJavaClass(Vehicle.class);
    descriptor.setTableName("VEHICLE");
    descriptor.setPrimaryKeyFieldName("ID");

    // Class indicators must be supplied for each of the subclasses in the  
    // hierarchy that can have instances.
    InheritancePolicy policy = descriptor.getInheritancePolicy();
    policy.setClassIndicatorFieldName("TYPE");
    policy.addClassIndicator(FueledVehicle.class, "Fueled");
    policy.addClassIndicator(Car.class, "Car");
    policy.addClassIndicator(Bicycle.class, "Bicycle");

    descriptor.addDirectMapping("id", "ID");
    descriptor.addDirectMapping("passengerCapacity", "CAP");

    return descriptor;
}

// FueledVehicle descriptor; it is a branch class and a subclass of Vehicle. 
// Queries made on this class will return instances of itself and instances of 
// its subclasses.
public static Descriptor descriptor() 
{
    Descriptor descriptor = new Descriptor();
    descriptor.setJavaClass(FueledVehicle.class);
    descriptor.addTableName("FUEL_VEH");
    descriptor.getInheritancePolicy().setParentClass(Vehicle.class);
    descriptor.addDirectMapping("fuelCapacity", "FUEL_CAP");
    descriptor.addDirectMapping("fuelType", "FUEL_TYPE");
    return descriptor;
}

// Car descriptor; it is a leaf class and subclass of FueledVehicle.
public static Descriptor descriptor() 
{
    Descriptor descriptor = new Descriptor();
    descriptor.setJavaClass(Car.class);
    descriptor.addTableName("CAR");
    descriptor.getInheritancePolicy().setParentClass(FueledVehicle.class);

    // Next define the attribute mappings.
    descriptor.addDirectMapping("description", "DESCRIP");
    descriptor.addDirectMapping("fuelType", "FUEL_VEH.FUEL_TYPE");
    return descriptor;
}

// NonFueledVehicle descriptor; it is a branch class and a subclass of Vehicle. 
// Queries made on this class will return instances of its subclasses.
public static Descriptor descriptor()
{
    Descriptor descriptor = new Descriptor();
    descriptor.setJavaClass(NonFueledVehicle.class);
    descriptor.getInheritancePolicy().setParentClass(Vehicle.class);
    return descriptor;
}

// Bicycle descriptor; it is a leaf class and subclass of NonFueledVehicle. 
public static Descriptor descriptor()
{
    Descriptor descriptor = new Descriptor();
    descriptor.setJavaClass(Bicycle.class);
    descriptor.getInheritancePolicy().setParentClass(NonFueledVehicle.class);
    descriptor.addDirectMapping("description", "BICY_DES");
    return descriptor;
}

/* FueledVehicle class; If a class extraction method is used, the following needs to be added to specify that only the branch class itself needs to be returned. This example is just specifying the class indicator field, which can also be specified in OracleAS TopLink Mapping Workbench in the Descriptor Advanced Properties dialog. */
public void addToDescriptor(Descriptor descriptor) 
{
    ExpressionBuilder builder = new ExpressionBuilder();
    descriptor.getInheritancePolicy().setOnlyInstancesExpression(
        builder.getField("VEHICLE.TYPE").equal("F")
    );
}

Example 3-53 Implementing a Multiple Table Descriptor In Which the Primary Keys Match

//Define a new descriptor that uses three tables.
Descriptor descriptor = new Descriptor();
descriptor.setJavaClass(Employee.class);
descriptor.addTableName("PERSONNEL"); // Primary table
descriptor.addTableName("EMPLOYMENT");
descriptor.addTableName("USERS");

descriptor.addPrimaryKeyFieldName("PER_NUMBER");
descriptor.addPrimaryKeyFieldName("DEP_NUMBER");

descriptor.addDirectMapping("id", "PER_NUMBER");
descriptor.addDirectMapping("firstName", "F_NAME");
descriptor.addDirectMapping("lastName", "L_NAME");

OneToOneMapping department = new OneToOneMapping();
department.setAttributeName("department");
department.setReferenceClass(Department.class);
department.setForeignKeyFieldName("DEP_NUMBER");
descriptor.addMapping(department);
// Mapping the primary key fields in the additional tables is not required
descriptor.addDirectMapping("salary", "EMPLOYMENT.SALARY");

AggregateObjectMapping period = new AggregateObjectMapping();
period.setAttributeName(period);
period.setReferenceClass(EmployementPeriod.class);
period.addFieldNameTranslation("EMPLOYMENT.S_DATE", "S_DATE");
period.addFieldNameTranslation("EMPLOYMENT.E_DATE", "E_DATE");
descriptor.addMapping(period);

descriptor.addDirectMapping("userName", "USERS.NAME");
descriptor.addDirectMapping("password", "USERS.PASSWORD");

Example 3-54 Implementing a Multiple Table Descriptor In Which the Additional Table Primary Keys are Named Differently

//Define a new descriptor that uses three tables.
Descriptor descriptor = new Descriptor();
descriptor.setJavaClass(Employee.class);
descriptor.addTableName("PERSONNEL"); 
// Primary table
descriptor.addTableName("EMPLOYMENT");
descriptor.addTableName("USERS");

descriptor.addPrimaryKeyFieldName("PER_NUMBER");
descriptor.addPrimaryKeyFieldName("DEP_NUMBER");

descriptor.addMultipleTablePrimaryKeyName("PERSONEL.PER_NUMBER",
  "USERS.PERSONEL_NO");
descriptor.addMultipleTablePrimaryKeyName("PERSONEL.DEP_NUMBER",
  "USERS.DEPARTMENT_NO");

// Assumed EMPLOYMENT uses same primary key
descriptor.addDirectMapping(id, PER_NUMBER);

OneToOneMapping department = new OneToOneMapping();
department.setAttributeName("department");
department.setReferenceClass(Department.class);
department.setForeignKeyFieldName("DEP_NUMBER");
descriptor.addMapping(department);

// Primary key does not have to be mapped for additional tables.
...

Example 3-55 Implementing Multiple Tables In Which a Foreign Key from the Primary Table to the Secondary Table Is Used to Join the Tables

Descriptor descriptor = new Descriptor();
descriptor.setJavaClass(Employee.class);
Vector vector = new Vector();
vector.addElement("EMPLOYEE");
vector.addElement(ADDRESS");
descriptor.setTableNames(vector);
descriptor.addPrimaryKeyFieldName("EMPLOYEE.EMP_ID");
// Map the foreign key field of the employee table and the primary key of the address table.
descriptor.addDirectMapping("addressID", "EMPLOYEE.ADDR_ID");

/* Setup the join from the address table to the country employee table to the address table by specifying the FK info to the descriptor. Set the foreign key info from the address table to the country table. */
descriptor.addMultipleTableForeignKeyFieldName("EMPLOYEE.ADDR_ID",
  "ADDRESS.ADDR_ID");

Example 3-56 Implementing Multiple Tables In Which You Specify a Join Expression and the Table Insert Order

Using this method allows only read and insert operations to be performed on Employee objects. Note that the primary key of the secondary table, and the foreign key of the primary table, must be mapped and maintained by the application for insert operations to work.

Descriptor descriptor = new Descriptor();
descriptor.setJavaClass(Employee.class);
Vector vector = new Vector();
vector.addElement("EMPLOYEE");
vector.addElement(ADDRESS");
descriptor.setTableNames(vector);

// Specify the primary key information for each table.
descriptor.addPrimaryKeyFieldName("EMPLOYEE.EMP_ID");

// Map the foreign key field of the employee table and the primary key of the 
// address table. 
descriptor.addDirectMapping("employee_addressID", "EMPLOYEE.ADDR_ID");
descriptor.addDirectMapping("address_addressID", "ADDRESS.ADDR_ID");
/* Setup the join from the employee table to the address table using a custom join expression and specifying the table insert order. */
ExpressionBuilder builder = new ExpressionBuilder();
descriptor.getQueryManager().setMultipleTableJoinExpression(builder.getField
  ("EMPLOYEE.ADDR_ID").equal(builder.getField("ADDRESS.ADDR_ID")));
Vector tables = new Vector(2);
tables.addElement(new DatabaseTable("ADDRESS"));
tables.addElement(new DatabaseTable("EMPLOYEE"));
descriptor.setMultipleTableInsertOrder(tables);
...

Example 3-57 Mapping a Multiple Table Descriptor In Which a Custom Join Expression is Required

In this example, only read operations are supported.

//Define a new descriptor that uses three tables.
Descriptor descriptor = new Descriptor();
descriptor.setJavaClass(Employee.class);
descriptor.addTableName("PERSONNEL"); 
// Primary table
descriptor.addTableName("EMPLOYMENT");
descriptor.addPrimaryKeyFieldName("PER_NO");
descriptor.addPrimaryKeyFieldName("DEP_NO");

ExpressionBuilder builder = new ExpressionBuilder();
descriptor.getQueryManager().setMultipleTableJoinExpression((builder.getField
  ("PERSONEL.EMP_NO").equal(builder.getField("EMPLOYMENT.EMP_NO")));
descriptor.addDirectMapping("personelNumber", "PER_NO");

OneToOneMapping department = new OneToOneMapping();
department.setAttributeName("department");
department.setReferenceClass(Department.class);
department.setForeignKeyFieldName("DEP_NO");
descriptor.addMapping(department);
// The primary key field on the EMPLOYMENT does not have to be mapped.
...

Example 3-59 Implementing Optimistic Locking Example

descriptor.useVersionLocking("VERSION");

The code in Example 3-59 stores the optimistic locking value in the identity map. If the value must be stored in a nonread-only mapping, then the code appears as follows:

descriptor.useVersionLocking("VERSION", false);

The false indicates that the lock value is not stored in the cache, but is stored in the object.