TopLink : attribute-mapping direct-xml-type-mapping

Question

hi
Using TopLink Workbench 10g Release 3 (10.1.3.0.0) Build 060118 it is possible to configure a "Direct to XML Type" mapping.
see http://www.oracle.com/technology/products/ias/toplink/doc/1013/main/_html/relmapun004.htm#CHDFIFEF
In the TopLink map this results in a
<opm:attribute-mapping xsi:type="toplink:direct-xml-type-mapping">Is there a way to configure this kind of attribute mapping using JDeveloper?
thanks
Jan Vervecken

Answer 1

Hi Paul,
The problem you're going to hit trying to do this with a TransformationMapping in 904 (as in my other post) is that during the UnitOfWork commit, when TopLink is checking for changes a .equals will end up being called on an XMLType instance which will throw a NullPointerException (in oracle.sql.Datum I think).
One way to work around this (depending on the requirements for your app) is to set the isMutable flag on the TransformationMapping to false. This flag indicates that the value in the object's attribute isn't going to be changed, so we don't bother trying to check to see if it's changed. This will allow you to do reads, inserts and deletes with no problems.
The downside is that if you need to be able to change the XML content in your objects model and do an update of the row, TopLink will never detect a change and never issue an update of the XMLType field.
Incidentilly, if you happen to hit the same issue you had with the DirectToXMLTypeMapping where you were getting back an instance of java.sql.Opaque instead of the expected oracle.xdb.XMLType from JDBC, you should be able to handle that case in your AttributeTransformer by doing
XMLType myXML = XMLType.createXML(myOpaque)
Document = myXML.getDocument();
Hope this helps
Matt MacIvor