Object-XML Mapping Concepts

Simple Type Translation

The simple type translation can be used with direct and direct collection mappings, allowing you to automatically translate an XML element value to an appropriate Java type based on the element's <type> attribute as defined in your XML schema.

In code, this is set up when building a mapping using the setIsTypedTextField method on XMLField, for example:

XMLDirectMapping mapping = new XMLDirectMapping();
XMLField tef = new XMLField();
tef.setIsTypedTextField(true);
tef.setXPath("NUMBER/text()");
mapping.setField(tef);
mapping.setAttributeName("number");
xmlDescriptor.addMapping(mapping); 

You can use simple type translation only when the mapping's XPath goes to a text node. You cannot use a simple type translation if the mapping's XPath goes to an attribute.

Using simple type translation, you can make the XML document preserve type information. This is useful when your object model specifies generic object attributes such as java.lang.Object and java.io.Serializable, since they do not trigger specific type conversions in EclipseLink as do specific object attributes such as java.lang.Integer or java.util.Calendar.

Figure 7-12 illustrates a type translation XML mapping for the number attribute of the PhoneNumber class. Notice that the Java attribute is not specific enough to preserve the typing. Simple type translation adds the type information to the resulting document to preserve the typing.

Figure 7-12 Simple Type Translation

Description of "Figure 7-12 Simple Type Translation"

By default, EclipseLink uses built-in read and write conversion pairs (see Default Read Conversions and Default Write Conversions).

You can override this behavior by specifying and configuring your own simple type translation, for example, to write XML binary data as Base64.