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Difference between revisions of "Creating an Object-Relational Data Type Descriptor (ELUG)"

m (How to Create an Object-Relational Data Type Descriptor Using Java)
m (227400)
 
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<span id="Example 30-1"></span>
 
<span id="Example 30-1"></span>
 
''''' Employee Class'''''
 
''''' Employee Class'''''
 +
<source lang="java">
 
  public class Employee {
 
  public class Employee {
 
     Long id;
 
     Long id;
Line 35: Line 36:
 
     ...
 
     ...
 
  }
 
  }
 
+
</source>
 
This example shows the object-relational data type database type (<tt>Employee_t</tt>) created to model the <tt>Employee</tt> object within the database. Such an object-relational data type database type is also known as a structure. This example also shows how to create and populate a database table (called <tt>department</tt>) that stores instances of the <tt>Employee_t</tt> audio tape.
 
This example shows the object-relational data type database type (<tt>Employee_t</tt>) created to model the <tt>Employee</tt> object within the database. Such an object-relational data type database type is also known as a structure. This example also shows how to create and populate a database table (called <tt>department</tt>) that stores instances of the <tt>Employee_t</tt> audio tape.
  
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<span id="Example 30-2"></span>
 
<span id="Example 30-2"></span>
 
''''' Employee Object-Relational Data Type Data Model'''''
 
''''' Employee Object-Relational Data Type Data Model'''''
 +
<source lang="sql">
 
  CREATE TYPE EMPLOYEE_T AS OBJECT(ID NUMBER(10),
 
  CREATE TYPE EMPLOYEE_T AS OBJECT(ID NUMBER(10),
 
                                   F_NAME VARCHAR2(100),
 
                                   F_NAME VARCHAR2(100),
 
                                   L_NAME VARCHAR2(100),) NOT FINAL;
 
                                   L_NAME VARCHAR2(100),) NOT FINAL;
 
  CREATE TABLE EMPLOYEES OF EMPLOYEE_T;
 
  CREATE TABLE EMPLOYEES OF EMPLOYEE_T;
 +
</source>
  
 
This example shows how to code an object-relational data type descriptor in Java to describe the object-relational data type database type <tt>Employee_t</tt>.
 
This example shows how to code an object-relational data type descriptor in Java to describe the object-relational data type database type <tt>Employee_t</tt>.
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<span id="Example 30-3"></span>
 
<span id="Example 30-3"></span>
 
''''' Creating an Object-Relational Data Type Descriptor in Java'''''
 
''''' Creating an Object-Relational Data Type Descriptor in Java'''''
 +
<source lang="java">
 
  import org.eclipse.persistence.mappings.structures.*;
 
  import org.eclipse.persistence.mappings.structures.*;
 
  ...
 
  ...
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  descriptor.addDirectMapping("firstName", "F_NAME");
 
  descriptor.addDirectMapping("firstName", "F_NAME");
 
  descriptor.addDirectMapping("lastName", "L_NAME");
 
  descriptor.addDirectMapping("lastName", "L_NAME");
 +
</source>
  
 
For more information on configuring object-relational data type descriptors, see [[Configuring%20an%20Object-Relational%20Data%20Type%20Descriptor%20(ELUG)|Configuring an Object-Relational Data Type Descriptor]].
 
For more information on configuring object-relational data type descriptors, see [[Configuring%20an%20Object-Relational%20Data%20Type%20Descriptor%20(ELUG)|Configuring an Object-Relational Data Type Descriptor]].

Latest revision as of 08:44, 20 May 2009

After you create a descriptor, you must configure its various options (see Configuring a Descriptor) and use it to define mappings.

For complete information on the various types of mapping that EclipseLink supports, see Introduction to Mappings and Creating a Mapping.

For complete information on the various types of descriptor that EclipseLink supports, see Descriptor Types.

For more information, see Introduction to Object-Relational Data Type Descriptors.


Creating an Object-Relational Data Type Descriptor

You cannot create an object-relational data type descriptor using the Workbench: you must use Java code. For more information on creating descriptors in Java code, see the EclipseLink API Reference.

For more information, see Object-Relational Data Type Descriptors.


How to Create an Object-Relational Data Type Descriptor Using Java

Use the ObjectRelationalDescriptor class to define an object-relational data type descriptor. This class extends RelationalDescriptor to add the following methods:

  • setStructureName: call this method to set the name of the object-relational data type structure that represents the object class in the data source.
  • addFieldOrdering: call this method repeatedly to define the order in which object attributes are persisted to the data source. This defines a field index that EclipseLink uses if your object-relational data type data source driver uses JDBC indexed arrays.

This example shows an Employee object that is mapped to an Oracle Database using its object-relational data type features.


Employee Class

 public class Employee {
     Long id;
     String firstName;
     String lastName;
 
     ...
 }

This example shows the object-relational data type database type (Employee_t) created to model the Employee object within the database. Such an object-relational data type database type is also known as a structure. This example also shows how to create and populate a database table (called department) that stores instances of the Employee_t audio tape.


Employee Object-Relational Data Type Data Model

 CREATE TYPE EMPLOYEE_T AS OBJECT(ID NUMBER(10),
                                  F_NAME VARCHAR2(100),
                                  L_NAME VARCHAR2(100),) NOT FINAL;
 CREATE TABLE EMPLOYEES OF EMPLOYEE_T;

This example shows how to code an object-relational data type descriptor in Java to describe the object-relational data type database type Employee_t.


Creating an Object-Relational Data Type Descriptor in Java

 import org.eclipse.persistence.mappings.structures.*;
 ...
 ObjectRelationalDescriptor descriptor = new ObjectRelationalDescriptor();
 descriptor.setJavaClass(Employee.class);
 descriptor.setTableName("EMPLOYEES");
 descriptor.setStructureName("EMPLOYEE_T");
 descriptor.setPrimaryKeyFieldName("ID");
 descriptor.addFieldOrdering("ID");
 descriptor.addFieldOrdering("F_NAME");
 descriptor.addFieldOrdering("L_NAME");
 descriptor.addDirectMapping("id", "OBJECT_ID");
 descriptor.addDirectMapping("firstName", "F_NAME");
 descriptor.addDirectMapping("lastName", "L_NAME");

For more information on configuring object-relational data type descriptors, see Configuring an Object-Relational Data Type Descriptor.

For more information on the object-relational data type mappings that EclipseLink supports, see Introduction to Object-Relational Data Type Mappings.




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