Package org.eclipse.persistence.oxm.mappings

Class XMLCompositeDirectCollectionMapping

  • All Implemented Interfaces:
    Serializable, Cloneable, DirectCollectionMapping<AbstractSession,​AttributeAccessor,​ContainerPolicy,​Converter,​ClassDescriptor,​DatabaseField,​XMLMarshaller,​Session,​XMLUnmarshaller,​XMLRecord>, Mapping<AbstractSession,​AttributeAccessor,​ContainerPolicy,​ClassDescriptor,​DatabaseField,​XMLRecord>, XMLContainerMapping, XMLConverterMapping<XMLMarshaller,​Session,​XMLUnmarshaller>, ContainerMapping, ArrayCollectionMapping, XMLMapping, XMLNillableMapping
    Direct Known Subclasses:
    XMLBinaryDataCollectionMapping
    public class XMLCompositeDirectCollectionMapping
extends AbstractCompositeDirectCollectionMapping
implements DirectCollectionMapping<AbstractSession,​AttributeAccessor,​ContainerPolicy,​Converter,​ClassDescriptor,​DatabaseField,​XMLMarshaller,​Session,​XMLUnmarshaller,​XMLRecord>, XMLMapping, XMLNillableMapping

    Composite direct collection XML mappings map a collection of simple types (String, Number, Date, etc.) to and from a sequence of composite XML nodes.

    Composite direct collection XML mappings can be used in the following scenarios:

    • Mapping to Multiple Text Nodes
    • Mapping to Multiple Attributes
    • Mapping to a Single Text Node
    • Mapping to a Single Attribute
    • Mapping to a List of Unions
    • Mapping a Union of Lists
    • Specifying the Content Type of a Collection

    Setting the XPath: TopLink XML mappings make use of an XPath statement to find the relevant data in an XML document. The XPath statement is relative to the context node specified in the descriptor. The XPath may contain node type, path, and positional information. The XPath is specified on the mapping using the setXPath method.

    The following XPath statements may be used to specify the location of XML data relating to an object's name attribute:

    XPath statements
    XPath Description
    @tasks The "@" character indicates that the node is an attribute. This XPath applies only to the single attribute node case; each member of the collection is mapped to a single node.
    tasks/@task The "@" character indicates that the node is an attribute. The information is stored in the attribute node of the tasks element.
    text() "text()" indicates that the node is a text node. In this case the task value in the text node belongs to the context node.
    tasks/text() The task information is stored in the text node of the tasks element.
    tasks/task/text() The XPath statement may be used to specify any valid path.
    task[2]/text() The XPath statement may contain positional information. In this case the task information is stored in the text node of the second occurrence of the task element.

    Mapping to a Single Text Node: By default, TopLink maps each member of a collection to it's own node. It is possible, however, to mapping a collection to a single node; here the contents of the node is treated as a space-separated list. This behavior is set on the mapping using the setUsesSingleNode method, with 'true' as the parameter.

    XML Schema
    <?xml version="1.0" encoding="UTF-8"?>
    <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
      <xsd:element name="employee" type="employee-type"/>
      <xsd:complexType name="employee-type">
        <xsd:sequence>
          <xsd:element name="tasks" type="tasks-type"/>
        </xsd:sequence>
      </xsd:complexType>
      <xsd:simpleType name="tasks-type">
        <xsd:list itemType="xsd:string"/>
      </xsd:simpleType>
    </xsd:schema>

    Code Sample
    XMLCompositeDirectCollectionMapping tasksMapping = new XMLCompositeDirectCollectionMapping();
    tasksMapping.setAttributeName("tasks");
    tasksMapping.setXPath("tasks/text()");
    tasksMapping.setUsesSingleNode(true);

    Specifying the Content Type of a Collection: By default, TopLink will treat the node values read in by a composite direct collection XML mapping as objects of type String. You can override this behavior by specifying the type of the collection's contents.

    XML Schema
    <?xml version="1.0" encoding="UTF-8"?>
    <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
      <xsd:element name="employee" type="employee-type"/>
      <xsd:complexType name="employee-type">
        <xsd:sequence>
          <xsd:element name="vacation" type="xsd:string" maxOccurs="unbounded"/>
        </xsd:sequence>
      </xsd:complexType>
    </xsd:schema>

    Code Sample
    XMLCompositeDirectCollectionMapping tasksMapping = new XMLCompositeDirectCollectionMapping();
    tasksMapping.setAttributeName("vacationDays");
    tasksMapping.setXPath("vacation/text()");
    tasksMapping.setAttributeElementClass(Calendar.class);

    Mapping to a List of Unions:

    XML Schema
    <?xml version="1.0" encoding="UTF-8"?>
    <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
      <xsd:element name="vacation" type="listOfUnions"/>
      <xsd:simpleType name="listOfUnions">
        <xsd:list>
          <xsd:simpleType>
            <xsd:union memberTypes="xsd:date xsd:integer"/>
          </xsd:simpleType>
        </xsd:list>
      </xsd:simpleType>
    </xsd:schema>

    Code Sample
    XMLCompositeDirectCollectionMapping mapping = new XMLCompositeDirectCollectionMapping();
    mapping.setAttributeName("myattribute");
    XMLUnionField field = new XMLUnionField("listOfUnions/text()");
    mapping.addSchemaType(new QName(url,XMLConstants.INT));
    mapping.addSchemaType(new QName(url,XMLConstants.DATE));
    mapping.setField(field);
    mapping.useSingleElement(false);

    More Information: For more information about using the XML Composite Direct Collection Mapping, see the "Understanding XML Mappings" chapter of the Oracle TopLink Developer's Guide.

    Since:
    Oracle TopLink 10g Release 2 (10.1.3)
    See Also:
    Serialized Form