Help on creating and deleting xml child elements using Toplink please.

Question

Hi there,
I am trying to build a toplink xml demo illustrating toplink acting as the layer between my java code and an xml datasource.
After pulling my custom schema into toplink and following the steps in http://www.oracle.com/technology/products/ias/toplink/preview/10.1.3dp3/howto/jaxb/index.htm related to
Click on Mapping Workbench Project...Click on From XML Schema (JAXB)...
I am able to set up java code which can run get and sets against my xml datasource. However, I want to also be able create and delete elements within the xml data for child elements.
i.e. in a simple scenario I have a xsd for departments which has an unbounded element of type employee. How does toplink allow me to add and or remove employees in a department on the marshalled xml data source? Only gets and sets for the elements seem accessible.
In my experience with database schema based toplink demos I have seen methods such as:
public void setEmployeesCollection(Collection EmployeesCollection) {
     this.employeesCollection = employeesCollection;
Is this functionality available for xml backended toplink projects?
cheers
Nick

Answer 1

Hi Nick,
Below I'll give an example of using the generated JAXB object model to remove and add a new node. The available APIs are defined in the JAXB spec. TopLink also supports mapping your own objects to XML, your own objects could contain more convenient APIs for adding or removing collection members
Example Schema
The following XML Schema will be used to generate a JAXB model.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
     elementFormDefault="qualified" attributeFormDefault="unqualified">
     <xs:element name="department">
          <xs:complexType>
               <xs:sequence>
                    <xs:element ref="employee" maxOccurs="unbounded"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
     <xs:element name="employee">
          <xs:complexType>
               <xs:sequence>
                    <xs:element name="name" type="xs:string"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
</xs:schema>---
Example Input
The following document will be used as input. For the purpose of this example this XML document is saved in a file called "employee-data.xml".
<department>
     <employee>
          <name>Anne</name>
     </employee>
     <employee>
          <name>Bob</name>
     </employee>
</department>---
Example Code
The following code demonstrates how to use the JAXB APIs to remove the object representing the first employee node, and to add a new Employee (with name = "Carol").
JAXBContext jaxbContext = JAXBContext.newInstance("your_context_path");
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
File file = new File("employee-data.xml");
Department department = (Department) unmarshaller.unmarshal(file);
// Remove the first employee in the list
department.getEmployee().remove(0);
// Add a new employee
ObjectFactory objectFactory = new ObjectFactory();
Employee newEmployee = objectFactory.createEmployee();
newEmployee.setName("Carol");
department.getEmployee().add(newEmployee);
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.marshal(department, System.out);---
Example Output
The following is the result of running the example code.
<department>
     <employee>
          <name>Bob</name>
     </employee>
     <employee>
          <name>Carol</name>
     </employee>
</department>